A series of new synthetic carbonaceous adsorbents has been prepared via physical and chemical activation of residue of alcoholic fermentation of corn starch. Two different variants of thermal treatment procedure -microwave and conventional heating have been applied for preparing of the activated biocarbons. All the samples under investigation were characterised by elementary analysis, surface area measurements as well as determination of the number of surface functional groups. The electrokinetic properties of examined materials were studied using potentiometric titration and electrophoresis methods, which enabled determination of the surface charge density and zeta potential of activated biocarbon particles. Moreover, sorption properties of the carbonaceous materials towards two organic dyes -methylene blue and malachite green were tested. The final products were activated biocarbons of medium developed surface area ranging from 21 to 879 m 2 /g, showing acidic character of the surface and various content of surface functional groups. More favourable textural parameters as well as sorption properties toward both organic dyes were revealed by chemically activated samples. The obtained results indicated also considerable effect of adsorbed dye molecules on the structure of electrical double layer formed at the solid/liquid interface.