A fuel for a fuel cell comprises a mixed solution of water and methanol, and an organic compound represented by the following formula (I) dissolved in the mixed solution as an antifreeze: (OH).sub.m--R.sup.1--R.sup.2--(OH).sub.n (I) where R.sup.1 and R.sup.2 each denote a radical having an indan or indene structure, which are either the same or different; and m and n are integers of 1 to 20.