A trifluorostyrene and substituted vinyl compound based partially fluorinated copolymer, an ionic conductive polymer membrane including the same, and a fuel cell adopting the ionic conductive polymer membrane, wherein the partially fluorinated copolymer has formula (1): ##STR00001## where each of R.sub.1, R.sub.2 and R.sub.3 is F, H or CH.sub.3; X is a hydroxy group or a trifluoromethyl group; m is an integer greater than zero; n is an integer greater than zero; and p, q and r are zero or integers greater than zero.