Abstract Small-sized spherical particles prepared from trimethylolpropane trimethacrylate (TRIM) containing both micro- and macro-pores were functionalized by polymerizing acryloyl chloride or methacryloyl chloride in their pore systems. The polymers formed are permanently attached to the particles, most probably by grafting to unreacted double bounds present in the TRIM particle matrix. In this way, composite particles containing 4 mmol of acid chloride groups per gram were obtained. A large proportion of the acid chloride polymers are located in the micropores of the TRIM particles, but the acid chloride groups can be quantitatively converted to esters or amides by reaction with alcohols or amines. This type of particles are useful as supports for metal phosphine complex catalysts, e.g., after reaction with N-methyl-4-(diphenylphosphino)benzylamine), or as stationary phases for chiral separation after reaction with S-phenylalanine ethyl ester.