The electric performances of direct borohydride fuel cells (DBFCs) are evaluated in terms of power density and life time with respect to the NaBH4 concentration. A DBFC constituted of an anionic membrane, a 0.6mgPt cm−2 anode and a commercial non-platinum based cathode led to performances as high as 200mWcm−2 at room temperature and with natural convection of air. Electrochemical life time test at 0.55mAcm−2 with a 5M NaBH4/1M NaOH solution shows a voltage diminution of 1mVh−1 and a drastic drop of performances after 250h. The life time is twice longer with 2M NaBH4/1M NaOH solution (450h) and the voltage decrease is 0.5mVh−1. Analyses of the components after life time tests indicate that voltage loss is mainly due to the degradation of the cathode performance. Crystallisation of carbonate and borate is observed at the cathode side, although the anionic membrane displays low permeability to borohydride.