Kinetic energy release distributions (KERDs) upon dissociation of proton-bound dimers are utilized along with finite heat bath theory analysis to obtain relative proton affinities of monomeric species composing the dimer. The proposed approach allows accurate measurement of relative proton affinities based on KERD measurements for the compound with unknown thermochemical properties vs a single reference base. It also allows distinguishing the cases when dissociation of proton-bound dimers is associated with a reverse activation barrier, for which both our approach and the kinetic method become inapplicable. Results are reported for the n-butanol-n-propanol dimer, for which there is no significant difference in entropy effects for two reactions, and for the pyrrolidine-1,2-ethylenediamine dimer, which is characterized by a significant difference in entropy effects for the two competing reactions. Relative protonation affinities of -1.0 +/- 0.3 kcal/mol for the n-butanol-n-propanol pair and 0.27 +/- 0.10 kcal/mol for the pyrrolidine-1,2-ethylenediamine pair are in good agreement with literature values. Relative reaction entropies were extracted from the branching ratio and KERD measurements. Good correspondence was found between the relative reaction entropies for the n-butanol-n-propanol dimer (Delta(DeltaS(double dagger)) = -0.3 +/- 1.5 cal/mol K) and the relative protonation entropy for the two monomers (Delta(DeltaS(p)) = 0). However, the relative reaction entropy for the pyrrolidine-1,2-ethylenediamine dimer is higher than the difference in protonation entropies (Delta(DeltaS(double dagger)) = 8.2 +/- 0.5 cal/mol K vs Delta(DeltaS(p)) = 5 cal/mol K).