Propylsulfonic acid-functionalized mesoporous silica materials were synthesized using a co-condensation technique. The catalytic performance of the resulting acidic mesoporous materials was evaluated in the methanol esterification of free fatty acids in beef tallow as a pretreatment step for alkyl ester production. The multicycle stability of the acid-functionalized mesoporous silica catalysts was studied. Issues concerning impurities in the feedstocks as well as a means of improving performance of the acidic solid catalyst through alternative strategies are discussed. Introduction of a hydrophobic group into the organosulfonic acid-functionalized mesoporous silica catalyst significantly enhanced the catalytic performance of the catalyst. The catalytic activity of the synthesized catalysts was compared to commercially available homogeneous and heterogeneous acidic catalysts.