The aim of this research was to study the deposition of platinum on Nafion117 membrane by using an electroless technique. The investigated parameters were electroless time (30 to 90 min) and Pt : N2H4 ratio (from 1 : 1 to 1 : 3.85). The results indicated that the platinum deposition on the 1st side of membrane was lower than that on the 2nd side because of the effect of N2H4 on the property of membrane. Platinum deposition increased when the Pt : N2H4 ratio decreased. The optimum condition was found at electroless time of 60 min and Pt : N2H4 ratio of 1 : 1.95. At this condition, more than 89% of platinum was deposited on both surfaces. The coated membrane was used to make a membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC) which was tested at 60 °C in a saturated H2/O2 system. The maximum current density was 80 mA/cm2 at 0.3 V.