A process for preparing a hybrid polyester-polyether polyol comprises contacting a carboxyl group-containing component and an epoxide, optionally in the presence of one or more of a double metal cyanide catalyst, a superacid catalyst, a metal salt of a superacid catalyst and/or a tertiary amine catalyst, under conditions such that a hybrid polyester-polyether polyol is formed. The hybrid polyester-polyether polyol offers the advantages of both ester and ether functionalities when used in a polyurethane formulation, thus enhancing physical properties. The process results in products having narrow polydispersity, a low acid number and unsaturation, and reduced byproduct formation, particularly when the double metal cyanide catalyst is employed.