utf-16le ?

encodings-1.py

import codecs

aaa = [ "aa", "bb", "cc", ]

with codecs.open("old.txt", mode='w', encoding='utf-16le') as f:
    f.write("\n".join(aaa) + "\n")

file_old = codecs.open('old.txt', mode='r', encoding='utf-16-le')
file_new = codecs.open('new.txt', mode='w', encoding='utf-16')

text = file_old.read().split("\\n")
print text
#bom = codecs.BOM_UTF16_LE
#file_new.write('\ufeff')
file_new.write("\r\n".join(text))
file_new.close()