We investigated the effect of temperature, oxidant and catalyst loading on the performance of direct formic acid fuel cell (DFAFC). When oxidant was changed from air to oxygen, the power density was increased to 17.3mW/cm2 at 25 ℃. The power density of DFAFC operated with oxygen showed a maximum value of 40.04 mW/cm2 with the temperature rise from room temperature to 70 ℃. The highest power density of DFAFC using air was observed for Pt-Ru black catalyst with loading of 8 mgPt/cm2 at room temperature. At 70 ℃; however, the performance of catalyst with the loading of 4mgPt/cm2 was higher than that of 8 mgPt/cm2. The DFAFC, operated with oxygen and catalyst of 4 mgPt/cm2 loading, showed the best performance at all temperature range. The enhancement of cell performance with an increase of catalyst loading is believed to come from an increase of catalyst active sites. However, operated at higher temperature or with oxygen, the cell with higher catalyst loading showed lower performance than expected. It is speculated that the thick catalyst layer inhibits the proton transport.