Due to factors including low emission values, great energy efficiency, and reduced environmental contamination, fuel cells have gained popularity recently. Fuel cells using polymer electrolyte membranes can distribute reactant gases through gas flow channels and remove water that forms during the reaction from the fuel cell. This study looked at how different channel sizes and channel cross-section geometries (rectangular, triangular, and semicircular) affected the distribution of current density, oxygen concentration, velocity, and temperature parameters on the cathode catalyst in the flow channels of a single-channel PEM fuel cell at 0.75 V cell voltage. The model with the highest current density and consequently the best fuel cell performance was determined to be 9 x 10-5 A/cm2 in a channel with a height and breadth of 0.1 cm and A = 1 cm2, according to the data obtained. The flow channel length was assessed at 0.2 in the analysis results for all models because it did not alter with the oxygen concentration distribution. In varied channel designs with the same area, it has been found that the velocity distribution varies inversely with the current density. The maximum velocity value recorded at this location was 33.1 m/s in a semicircular canal with a R of 0.34 mm. It has been discovered that fuel cells from more places operate better as a result.