The kinetics and mechanism of ethene dimerization and allene oligomerization with monometallic rhodium complexes in aqua-alcohol solvents have been studied. Both dielectric permeability and electroconductivity of solvents have been found to affect the kinetics of the reactions. The experimental evidence and quantum chemical analysis of elementary steps of the reactions allowed proposing a unified
scheme for active sites generation under catalytic transformation of unsaturated hydrocarbons by the use of rhodium complexes in protic solvents.