MoO3/ZrO2, a solid Bronsted acid, exhibited high catalytic performance for the polyesterification of adipic acid with 1,4-butanediol: the conversion of adipic acid exceeds 95% over 8 h. The amount of residual Mo species that induce the hydrolysis of ester bonds with atmospheric vapors was below 3 ppm in the resulting polymer. After reaction, the MoO3/ZrO2 catalyst was easily recovered by simple filtration and used repeatedly without significant loss of original activity for subsequent reactions.