The discrepancy between the charge number (number of strongly acidic groups) of latex determined by conductometric titration and that by shear modulus titration, which has been pointed out by Palberg et al, (J. Colloid Interface Sci. 169, 85 (1995)), is critically discussed, It is suggested that the reported discrepancy can be ascribed to an overestimation of the strong acidic group content by the conductometric method, caused by coexisting weakly acidic groups on the latex used. When the number of weak acidic groups is negligibly small, the neutralization point determined by the conductometric titration agrees well with that by the viscometric titration.