i trying make join of lists within list in python here example of doing (the lists bigger in real code): import itertools listenv = ["in","vc","vs"] listsize = ["u17-1","u17-2"] listevnsize = list(itertools.product(listenv, listsize,)) print listevnsize #this results in [('in', 'u17-1'), ('in', 'u17-2'), ('vc', 'u17-1'), ('vc', 'u17-2'), ('vs', 'u17-1'), ('vs', 'u17-2')] what want combine inner lists - instance result be: [('in-u17-1'), ('in-u17-2'), ('vc-u17-1'), ('vc-u17-2'), ('vs-u17-1'), ('vs-u17-2')] so in other words join inner lists, when tried using: listevnsizejoined = '-'.join(map(str,listevnsizezip)) as suggested in question, joining of outer lists 1 big string this: (('in', 'u17-1'),)-(('in', 'u17-2'),)-(('vc', ...