The alkylation of toluene, ethylbenzene, cumene, and xylenes with ethene, propene, and 1,2-diphenylethylene was investigated over superbasic MgO-K and gamma -Al2O3-K catalysts and over model systems of the EDA complex type. Metal oxide-alkali metal solid superbases as well as MgO-K polyaromatic hydrocarbon systems exhibited high activity in the transformations carried out under atmospheric and elevated pressure at low temperature. The reaction kinetics, the results of ESR investigations of adsorbed intermediates, and the effects of poisoning using radicals trap TEMPO enabled the identification of F-s(+) sites as catalytically active centres. The proposal of a radical pathway of the reaction was confirmed and illustrated.