The release profiles of acidic form of diclofenac sodium adsorbed on mesoporous silicas (Silochrom and two samples of spherical silicas) were compared with the dissolution characteristics of the pure drug. Desorption of diclofenac sodium from impregnated silicas with various surface liophilicity and composites of silica with chitosan have been studied using rotating basket method in phosphate buffer, pH 6.8. Sedimentations of sodium diclofenac via adsorption and impregnation from alcohol solution on fumed silica and modified silicas with grafted aminopropyl and trimethylsilyl groups were carried out. Polymer-containing composites have been prepared by capsulation of silica particles with impregnated diclofenac sodium by protonated and deprotonated forms of chitosan. Effect of the silica surface nature on the active substance release rate was ascertained. Significant prolongation of diclofenac sodium release was detected in the case of application of hydrophobic silica as a carrier and protonated chitosan as a polymeric shell.