The adsorption isotherms of 10 different adsorptives have been measured at different temperatures over a large relative pressure range onto a suite of commercial activated carbons with different extents of activation. The experimental results were evaluated by means of BET, Aranovich and Dubinin equations. Micropore distribution functions were calculated by use of the Jaroniec-Choma model and regularization method. The obtained parameters and pore size distributions showed significant dependences between the microporosity of the samples and the level of activation. The micropore distribution functions calculated by use of regularization method point out to problems of the DR-equation as local isotherm.