A series of highly active, selective, and stable silver-exchanged phosphotungstic acid (AgPW) catalysts were prepared, characterized, and evaluated for bio-derived glycerol esterification with acetic acid to produce valuable biofuel additives. The structures, morphologies, acidities, and water tolerance of these samples were determined by FTIR, Raman, XRD, SEM-EDX, FT-IR of pyridine adsorption, and H 2 O-TPD. Several typical acidic catalysts were also performed for comparison. Among them, partially silver-exchanged phosphotungstic acid (Ag 1 PW) presented exceptionally high activity, with 96.8% conversion within just 15min of reaction time and remarkable stability, due to the unique Keggin structure, high acidity as well as outstanding water-tolerance property. A plausible reaction mechanism was also proposed. In addition, this Ag 1 PW catalyst exhibited universal significance for esterification, holding great potential for a wide range of other acid-catalyzed reactions.