The voltammetry of N,N-dimethyl-p-phenylenediamine, DMPD, in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tetrafluoroborate, [C(4)mim][BF(4)] is studied by means of microdisc voltammetry over a wide range of voltage scan rates incorporating the transition from linear to convergent diffusion. Two voltammetric waves were recorded corresponding to the formation of the radical cation DMPD(+) and dication DMPD(2+); both are stable on the voltammetric time scale. Double potential step chronoamperometry was used to measure the diffusion coefficients of DMPD and DMPD(+). These values, in conjunction with simulations of the cyclic voltammetry, permit the inference of the equilibrium constant and kinetics for the comproportionation of DMPD and DMPD(2+) forming DMPD(+) to be studied.