Hydration phenomena at cement/water interfaces drive the characteristics of oil-well cement slurries. In this study, new epoxy-modified cement slurries were synthesized. The slurries characterization has suggested the presence of low amounts of portlandite in the slurry with the higher content of polymerized epoxy resin. The hydration processes of the cement slurries were studied by heat-conduction microcalorimetry. The energetic and enthalpic hydration data were all exothermic in nature. The cumulative heat release curves have shown the presence of multilinearity of the kinetic processes. The hydration micro-calorimetric data were well fitted to the multistep Avrami kinetic model. it was found that the epoxy-modified cement slurries present a good potential to be used in environmental-friendly oil-well operations. (C) 2009 Elsevier Inc. All rights reserved.