Poly(cis-1,4-butadiene) (PCB) gels were prepared by the crosslinking polymerization of 4-tert-butylstyrene (tBS) and divinylbenzene (DVB) onto unvulcanized butadiene rubber with a solution polymerization technique with benzoyl peroxide (BPO) as an initiator. The effects of the reaction conditions, such as the amount of the solvent, the amount of DVB and tBS, and the initiator (BPO), on the equilibrium swelling ratio (Q(e)) were also investigated. The highest oil absorbencies of crosslinked gels in xylene and cyclohexane were 51.35 and 32.98 g/g, respectively. A swelling kinetic equation was roposed for this system: Q(t) = Q(e) -{Kt + [1/Q(e) - Q(0))}(-1) where Q(t) is the swelling ratio at time t, Q(0) is the initial swelling ratio, and K is the swelling kinetic constant. This equation fit the experimental results quite well. The diffusion of organic solvents in PCB gels was Fickian. (C) 2003 Wiley Periodicals, Inc.