Abstract Some four-component random phenolic copolymers were prepared from four typical phenolic monomers; for example, p-nitro-phenol, p-chlorophenol, p-aminobenzoic acid, and p-hydroxybenzoic acid. Several samples of the copolymer were prepared by changing the feed composition, and the composition of the copolymers was established by estimating -NH2 and -OH groups by electrometric titration technique in nonaqueous media. Halogen was estimated by Volhard's method. The composition of the copolymers could be accounted for on the basis of the structure of the monomeric species. Hyperacidity of some of the functional groups in the copolymer chain is interpreted in terms of intramolecular hydrogen bonding.