The two anti-scale agents BELGARD EV (BELEV) and BELGARD EV 2000 (BELEV 2) are titrated against standard NaOH solution. Both the potentiometric (pH metric) and the conductometric titration techniques are used. For the sake of comparison the reaction of the monomer (maleic acid, H(2)M) is also investigated. The two titration techniques reveal that H(2)M neutralizes along two equal steps. The pK(1) and pK(2) of the acid are calculated as 2.9 and 6.1, in good agreement with the values quoted in the literature. The potentiometric titration curves of BELEV and BELEV 2 solutions are similar and show a single drawn-out inflexion. Computer analysis of the curves reveal four acid species in case of BELEV and two in case of BELEV 2. The pK values, the percentage composition and the mean average molecular weights of all species are computed. The consumption of NaOH till any one and the same pH value varies linearly with the additives content in solution. This offers a simple method for analysis of BELEV and BELEV 2 preparations. The conductometric titration curves of the two agents indicate the presence of three acid species. Correlation with the pH curves is made in every case. Not all the inflexions in conductometric curves have correspondence in pH curves. The effect of addition of increasing concentrations of H(2)M to BELEV (BELEV 2) solutions and of increasing BELEV (BELEV 2) concentrations to H(2)M on the pH-metric curves is examined in detail. The two materials affect the neutralization pattern of one another. The results suggest the masking of the free-acid protons through hydrogen bonding with the polymers.