In this study, styrene(St)/2-ethyl hexyl acrylate(2-EHA) based surface sizing materials were developed with four different cationic monomers (CM), namely diallyldimethyl ammonium chloride (DADMAC), [2-(methacryloyloxy) ethyl] trimethylammonium chloride (MATMAC), [3-(methacryloylamino) propyl]-trimethyl ammonium chloride (MAPTAC), (viniylbenzyl) trimethyl-ammonium chloride (VBTMAC). Ternary polymerization was realized with emulsion polymerization, by using 2,2'-azobis (2-methylpropionamidine) dihydrochloride (A) as initiator. Thermal properties of the synthesized terpolymers were determined with differential scanning calorimeter and thermal gravimetric analysis. Differential scanning calorimeter results showed that glass transition temperature (T-g) values of polymers were not dependent on the types of cationic monomers, and were found about 44-45 degrees C. Ion exchange capacities of the terpolymers were determined. The latexes produced were used as sizing materials for paper surface treatment. Then critical surface properties of the papers sized such as water resistance (Cobb value) and contact angle were measured. It was found that the best, i.e. the lowest Cobb results were obtained when MATMAC and MAPTAC cationic monomers were used in terpolymers.