# credit to Stack Overflow user in the source link
# requires LibreOffice installed
import os
import subprocess
for top, dirs, files in os.walk('/my/pdf/folder'):
for filename in files:
if filename.endswith('.pdf'):
abspath = os.path.join(top, filename)
subprocess.call('lowriter --invisible --convert-to doc "{}"' # bash/shell syntax
.format(abspath), shell=True)