The treatment of cardboards and papers by means of colloid-graphite water dispersions was suggested for manufacturing the materials with surface electrical resistivity rho(S) in the range of similar to 10(1) to 10(6) Omega. It is shown that low-frequency ac conductivity of the colloid dispersion can be used for the treatment process control. The samples of electrically conductive paper with rho(S) = 20 Omega were produced. Different types of the electroconductive cardboards and papers were studied by means of both do techniques, and the microwave surface resistivity measurements. The problem of the optimal parameters of electroconductive papers for electromagnetic wave absorbers is discussed. The dependences of electrophysical properties of cardboard after the treatment on processing time and concentration of the colloidal-graphite solution are presented. (C) 2007 Elsevier B.V. All rights reserved.