The effects of tri-, di- and monocarboxylate on the growth of nanoparticles of calcium oxalate (CaOxa) were first investigated in liposome system. Sodium acetate (NaAc) only induced calcium oxalate monohydrate (COM), while sodium tartrate (Na(2)tart) and sodium citrate (Na(3)cit) could induce calcium oxalate dihydrate (COD) with a preferential growth of (213) crystal face. The promotion effectiveness to COD followed this order: Na(3)cit > Na(2)tart > NaAc.