Easy, safe, and cost-effective hydroxyl-containing microporous hyper-cross-linked polymers based on phenol (pPhOH) and 4,4'-(propane-2,2-diyl)diphenol (or bisphenol A; BPA) were prepared by the Friedel-Crafts alkylation reaction of phenol and bisphenol A using dimethoxymethane as an external cross-linker. The pPhOH and pBPA were functionalized by chlorosulfonic acid to yield corresponding sulfonic acid-functionalized polymers, pPh-SO3H and pBPA-SO3H, respectively, with their surface areas of 210 m(2)/g and 324 m(2)/g, respectively. The physicochemical properties of pPh-SO3H and pBPA-SO3H were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, Brunauer-Emmett-Teller analysis, and X-ray photoelectron spectroscopy. The pPh-SO3H and pBPA-SO3H polymers show excellent catalytic activity for the esterification of free fatty acids and transesterification of vegetable oils at room temperature, as well as excellent recyclability, signifying the potential of these porous polymers in a wide array of eco-friendly acid-promoted chemical transformations.