diff --git a/test/lint/lint-python-format-tests.txt b/test/lint/lint-python-format-tests.txt
new file mode 100644
--- /dev/null
+++ b/test/lint/lint-python-format-tests.txt
@@ -0,0 +1,43 @@
+# This file contains python code with % string formatters to test the 
+# lint-python-format.py script.
+
+# Single line
+"test %s" % "string"
+"pi %.2f" % 3.1415
+
+# Multiple lines
+"test %s" %
+    "string"
+"test %s" % \
+    "string"
+"test %s" \
+    % "string"
+"test %s %s %s" \
+    % ("1", "2", "3")
+"test %s %s %s" % \
+    ("1", "2", "3")
+"test %s %s %s" \
+     % ("1",
+    "2", "3")
+"test %s %s %s" \
+   % ("0" \
+   + "1",
+  "2", "3")
+
+# In a comment
+# "test %s" % "string"
+
+# Nested comment
+"test %s %s %s" \
+    % ("1",
+    #"4",
+    "2", "3")
+    
+# Inlined comments are not supported
+# "test %s %s %s" \
+#     % ("1", #4,
+#     "2", "3")
+
+# Nested format inside a list or dict is not supported
+# ["test %s" % "string"]
+# will replace with => ["test %s".format("string"])
\ No newline at end of file
diff --git a/test/lint/lint-python-format.py b/test/lint/lint-python-format.py
new file mode 100755
--- /dev/null
+++ b/test/lint/lint-python-format.py
@@ -0,0 +1,184 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2019 The Bitcoin developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+# Lint python format : This program checks that the old python fomatting method
+# is not being used (formatting with "string %s" % content).
+# The new "{}".format(content) or f"{} content" method should be used instead.
+# Usage of the % formatter is expected to be deprecated by python in the future.
+
+import re
+import sys
+from doctest import testmod
+
+
+def is_complete(snippet):
+    r"""Check if a code snippet is complete.
+
+    >>> is_complete("a = [1, 2, 3]")
+    True
+    >>> is_complete("a = [1,")
+    False
+    >>> is_complete("a = [1, (")
+    False
+    >>> is_complete("a = [")
+    False
+    >>> is_complete("a = [1, {")
+    False
+    >>> is_complete('a = [1, 2, "%d" %    \\')
+    False
+    >>> is_complete('a = [1, 2, \"\"\"')
+    False
+    >>> is_complete('"%s" %')
+    False
+    """
+    can_continue = [',', '(', '[', '{', '\\', '"""', '%']
+    return not any(snippet.strip().endswith(end) for end in can_continue)
+
+
+def build_replacement(error):
+    r"""Replace a snippet using the % formatter with a version using .format().
+
+    >>> build_replacement('"test %s" % "1"')
+    '"test {:s}".format("1")'
+    >>> build_replacement('"test %.2f" % 3.1415')
+    '"test {:.2f}".format(3.1415)'
+    >>> build_replacement('"test %s" \\\n% "1"')
+    '"test {:s}".format("1")'
+    >>> build_replacement('"test %s" %\\\n"1"')
+    '"test {:s}".format("1")'
+    >>> build_replacement('"test %s %s %s" % ("1", "2", "3")')
+    '"test {:s} {:s} {:s}".format("1", "2", "3")'
+    >>> build_replacement('"test %s %s %s" % \\\n("1", "2", "3")')
+    '"test {:s} {:s} {:s}".format("1", "2", "3")'
+    >>> build_replacement('"test %s %s %s" % \\\n("1",\n"2", "3")')
+    '"test {:s} {:s} {:s}".format("1", "2", "3")'
+    """
+    # Inline the error snippet.
+    # Replace line continuation ('\'), line breaks and their surrounding
+    # spaces and indentation to a single space character
+    replacement = re.sub(r"\s*\\\s+", " ", error, re.MULTILINE)
+    replacement = re.sub(r"\s*(?:\r?\n|\r(?!\n))\s*",
+                         " ", replacement, re.MULTILINE)
+
+    # Replace the specifiers, retaining their content.
+    # E.g. %.2f => {:.2f}
+    def specifier_sub(match):
+        return "{:" + match.group(1) + "}"
+
+    (replacement, count) = re.subn(
+        r"%([a-zA-Z0-9.]+)", specifier_sub, replacement, flags=re.MULTILINE)
+
+    # Replace the qualifier.
+    # E.g % 42 => .format(42)
+    # E.g. % (42, "my_string") => .format(42, "my_string")
+    def qualifier_sub(match):
+        qualifier_sub.qualifier += match.group(1).strip()
+        return qualifier_sub.qualifier
+
+    qualifier_sub.qualifier = ".format("
+    if count > 1:
+        # If more that 1 specifier, % expects a tuple starting with '('
+        replacement = re.sub(r"\s+%\s+\((.+)", qualifier_sub, replacement,
+                             flags=re.MULTILINE)
+    else:
+        # Otherwise there is no parenthesis
+        replacement = re.sub(r"\s+%\s+(.+)", qualifier_sub, replacement,
+                             flags=re.MULTILINE) + ")"
+
+    return replacement
+
+
+def find_snippets(file):
+    """Find code snippets in the source file that contains the percent ('%')
+    character"""
+    with open(file, 'r') as f:
+        snippet_line = ""
+        snippets = {}
+
+        for line_number, line in enumerate(f):
+            # Skip comments
+            if not line.strip().startswith('#'):
+                # If we are not already in a snippet and the line contains a %
+                # character, start saving the snippet
+                if not snippet_line and '%' in line:
+                    snippet_line = str(line_number + 1)
+                    snippets[snippet_line] = ""
+
+                # In a snippet ?
+                # - save the line
+                # - check if the snippet is complete
+                if snippet_line:
+                    snippets[snippet_line] += line
+                    if is_complete(line):
+                        snippet_line = ""
+
+    return snippets
+
+
+def find_errors(file):
+    """Extract snippets using the % symbol as a formatter with their line
+    number"""
+    pattern = re.compile(r"(?:\"|')\s*\\?\s+%\s+(?:\\\s+)?.+$", re.MULTILINE)
+    snippets = find_snippets(file)
+    return dict(
+        [(l, s) for l, s in snippets.items() if pattern.search(s) is not None])
+
+
+def main(file):
+    r"""Print line number and code snippets using the % formatter from the file,
+    and suggest a replacement using the .format() method.
+    Output format is :
+    (<line number>) <original snippet>
+    => <replacement snippet>
+
+    >>> main("test/lint/lint-python-format-tests.txt")
+    (5) "test %s" % "string"
+    => "test {:s}".format("string")
+    (6) "pi %.2f" % 3.1415
+    => "pi {:.2f}".format(3.1415)
+    (9) "test %s" %
+        "string"
+    => "test {:s}".format("string")
+    (11) "test %s" % \
+        "string"
+    => "test {:s}".format("string")
+    (13) "test %s" \
+        % "string"
+    => "test {:s}".format("string")
+    (15) "test %s %s %s" \
+        % ("1", "2", "3")
+    => "test {:s} {:s} {:s}".format("1", "2", "3")
+    (17) "test %s %s %s" % \
+        ("1", "2", "3")
+    => "test {:s} {:s} {:s}".format("1", "2", "3")
+    (19) "test %s %s %s" \
+         % ("1",
+        "2", "3")
+    => "test {:s} {:s} {:s}".format("1", "2", "3")
+    (22) "test %s %s %s" \
+       % ("0" \
+       + "1",
+      "2", "3")
+    => "test {:s} {:s} {:s}".format("0" + "1", "2", "3")
+    (31) "test %s %s %s" \
+        % ("1",
+        "2", "3")
+    => "test {:s} {:s} {:s}".format("1", "2", "3")
+    """
+    errors = find_errors(file)
+    # Python dictionnaries do not guarantee ordering, sort by line number
+    for line_number, error in sorted(errors.items(),
+                                     key=lambda pair: int(pair[0])):
+        replacement = build_replacement(error)
+        print("({}) {}".format(line_number, error.rstrip()))
+        print("=> " + replacement)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        sys.exit(testmod()[1])
+    else:
+        main(sys.argv[1])