The common theory of reversible charge transfer (RCT) at low donor system excitation power in liquids is examined. The space averaging procedures describing the kinetics of RCT in the liquid space are discussed. The reaction space is presented as a totality of independent subgroups with one excited donor and some group of acceptors effectively interacting only with the donor in the given "subgroup". We have shown that the theory [3-5] gives questionable results for cation state probability for the usual parameters of this problem. If the acceptor concentration or the charge transfer rate constants are low, then the cation state probability behaves the same in the two theories [3-5] and [7, 8]. The correct account of the donor's ground state change and charge back transfer in the RCT theory gives the new, not contradictory results, different from the behavior of the results in references [3-5], but near to results of [7, 8]. The molecules motion accelerates the ionization of donors and neutralization of ions. The influence of the motion of neutral and ionized molecules on charge transfer kinetics is different. The Coulomb interaction of ions is taken into account; the effect depends on the space averaging method used. The new approximation in this article in comparison with references [3-6, 9] consists in the space averaging procedure of the donor cation state probability, which takes into account the donor's ground state.