Abstract Cementing wellbores drilled in low-temperature formations such as permafrost and gas-hydrate zones requires cement compositions that set at low temperatures and yet have low heat-of-hydration. This is particularly the case for gas-hydrate zones because of the potential for gas liberation from gas hydrates and formation of gas flow channels if the temperature rise caused by heat-of-hydration exceeds the temperature at which gas hydrates decompose. This paper presents novel cement compositions that contain heat-sink additives capable of absorbing heat released from cement hydration without a significant rise in the slurry temperature. The organic heat-sink materials are added to cement slurries as aqueous suspensions or emulsions and undergo phase changes when heated. The slurry temperature rise caused by cement hydration in the presence of these materials was measured under adiabatic conditions and the results are presented.