This paper brings information regarding the hydration-hydrolysis processes of some blended cements with limestone filler or fly ash additions and of composite Portland cements (II/A-M, II/B-M type – with limestone filler and fly ash). The evolution of the hydration-hydrolysis processes and the nature of the hydrates formed in the binding systems were investigated by the assessment measurements of the CaO content in solution, pH and electrical conductivity measurements on suspensions, differential thermal analysis and X-ray diffraction on pastes hardened different periods of time.