Optimisation of process parameters for the removal of calcium ions by phenol-formaldehyde sulphonic ac id resin (PFR) blended with sulphonated carbons (SCs) obtain ed from various plant materials like AA, EJ and TB was carried out by using Box-Behnken statistics and ana lysis of variance method. Response surface methodo logy with three levels of process parameters viz., % (w/w), o f SC in condensate (10, 20 and 30), particle size ( 200, 300 and 400 μ m or microns) and initial concentration of calcium ions (0.05, 0.1 and 0.15 mol L -1 ) were used in the identification of significance of the effects and i nteractions in ion exchange studies. Response surf ace methodology requires no assumption and identifies the experimen tal variables and their interactions which have the greatest effect on ion exchange process. The optimum proces s parameters for maximum removal of calcium ions we re obtained by this procedure. Contour plots were obta ined and interpreted.