The effects of different alcohol molecular configurations and resin structures were analyzed on the sulfonic acid-resin catalyzed addition of alcohols to epoxidized fatty esters. Emphasis was placed on the addition of a-and b-branched alcohols. Regarding the catalysts, the effect of the acid strength as well as that of the diffusion constraints on the reaction rate and products distributions, were determined. Reaction rate increases with the acid strength but the selectivity shows the opposite trend when highly branched alcohols are added. Epoxide ring-opening rate decreases by increasing the number of branches and size of the alcohol. Branches in a position introduce a higher steric hindrance than branches in b position. Low resin crosslinkage and/or high external surface area are necessary conditions to activate the epoxide when polystyrene-based resins are used as catalysts. The obtained byproducts were the ketone, from epoxide rearrangement, and trans-esterified products, when reaction times were relatively long.