The surface charge of polymeric or other type of materials is attributed to the ionization of functional groups, -OH, -COOH, -SO3H etc., which promote the formation of inorganic scale deposits. Contact of the charged matrices with supersaturated solutions with respect to calcium phosphate, result to locally higher supersaturation on their surface with respect to the corresponding scale minerals. Poly-2-hydroxyethyl methacrylate, (PHEMA) a hydrophilic polymer with ionized -OH functional groups, was highly negative, negative charge increasing with increasing pH. The formation of HAP from calcium phosphate supersaturated solutions inoculated with PHEMA, increased synergistically the surface charge of the composite PHEMA-HAP in comparison with each component separately. Polymethyl methacrylate (PMMA), a hydrophobic polymer of significantly less negative surface charge, did not favor nucleation and crystal growth of HAP. The results suggest that zeta potential may be a useful indicator for the propensity of materials to form inorganic scales through heterogeneous nucleation.