The kinetics of charge recombination between the primary photoxidized donor (P⁺) and the secondary reduced quinone acceptor (Q_B⁻) have been studied in reaction centers (RCs) from the purple photosynthetic bacterium Rhodobacter sphaeroides incorporated into lecithin vesicles containing large ubiquinone pools over the temperature range 275K≤T≤307K. To account for the non-exponential kinetics of P⁺ re-reduction observed following a flash, a new approach has been developed, based on the following assumptions: 1) the exchange of quinone between different vesicles is negligible; 2) the exchange of quinone between the Q_B site of the RC and the quinone pool within each single vesicle is faster than the return of the electron from the primary reduced acceptor Q_A⁻ to P⁺; 3) the size polydispersity of proteoliposomes and the distribution of quinone molecules among them result in a quinone concentration distribution function, P(Q). The first and second moments of P(Q) have been evaluated from the size distribution of proteoliposomes probed by quasi-elastic light scattering (mean radius, 〈R〉=(50±15) nm). Following these premises, we describe the kinetics of P⁺Q_B⁻ recombination with a truncated cumulant expansion and relate it to P(Q) and to the free energy changes for Q_A⁻Q_B→Q_AQ_B⁻ electron transfer (ΔG_AB^o) and for quinone binding (ΔG_bind^o) at Q_B. The model accounts well for the temperature and quinone dependence of the charge recombination kinetics, yielding ΔG_AB^o=−7.67±0.05kJmol⁻¹ and ΔG_bind^o=−14.6±0.6kJmol⁻¹ at 298K.