The present invention is directed to a golf ball having at least one layer formed from a moisture resistant, highly neutralized acid polymer composition. Highly neutralized acid polymers of the present invention are produced with a cation source selected from ions and compounds of lithium, ions and compounds of zinc, and combinations thereof. Golf balls of the present invention include one-piece, two-piece, multi-layer, and wound golf balls. The composition may be present in any one or more of a core layer, a cover layer, or an intermediate layer.