The organic-inorganic hybrid catalysts, namely [GlyH](x)H3-xPW12O40 (x = 1.0-3.0), prepared by mixing varied amounts of glycine (Gly) and tungstophosphoric acid (TPA), were characterized by different analytical and spectroscopic techniques such as TGA, XRD, FT-IR, and H-1 and C-13 NMR. In particular, their acidic properties were probed by solid-state 31P MAS NMR of adsorbed trimethylphosphine oxide. The catalytic performances of various Gly-TPA catalysts during esterification reaction of palmitic acid with methanol for production of methyl palmitate were illustrated and examined. The catalyst system revealed self-separation characteristics, forming biphasic product/catalyst layers to render facile product separation and catalyst recycling. The [GlyH](1.0)H2.0PW12O40 catalyst was found to exhibit the best activity with an optimal biodiesel yield of 93.3%. (C) 2015 Elsevier Ltd. All rights reserved.