The present invention is directed to a crosslinkable polymer composition comprising an alkoxysilane functional polyolefin and a silanol crosslinking catalyst selected from the group consisting of: (i) an alkylated naphthalene monosulfonic acid substituted with 1-4 alkyl groups wherein each alkyl group is a linear or branched alkyl with 5-20 carbons with each alkyl group being the same or different, wherein the total number of carbons in the alkyl groups is in the range of 20 to 80 carbons; (ii) an arylalkyl sulfonic acid wherein the aryl is phenyl or naphthyl and is substituted with 1-4 alkyl groups wherein each alkyl group is a linear or branched alkyl with 5-20 carbons with each alkyl group being the same or different, and wherein the total number of carbons in the alkyl groups is in the range of 12-80; (iii) a derivative of (i) or (ii) selected from the group consisting of an anhydride, an ester, an acetylate, an epoxy blocked ester and an amine salt thereof which is hydrolyzable to the corresponding alkyl naphthalene monosulfonic acid or the arylalkyl sulfonic acid; (iv) a metal salt of (i) or (ii) wherein the metal ion is selected from the group consisting of copper, aluminum, tin and zinc, and to a process for crosslinking an alkoxysilane functional polyolefin using a catalyst as defined above.