A golf ball having a layer composed of a polyurethane/polyurea material formed from reaction injection molding a polyol component and an isocyanate component. The polyol component preferably comprises a polytetramethylene ether glycol having a molecular weight of approximately 1000 and a 3,5-diethyl-2,4 toluenediamine. The layer is preferably a cover layer having a thickness ranging from 0.010 inch to 0.025 inch.