The effect of chemically inert nanoparticles of anatase titanium dioxide (TiO2) on hydration rate of belite (β-C2S) was studied using isothermal calorimetry. The TiO2 was added to β-C2S paste at 0%, 5%, and 10% by mass. The results indicate that the addition of TiO2 nanoparticles shorten the induction period and accelerate hydration beyond 3 days, showing rate peaks at 40 days of age. The cumulative heat data suggests that TiO2-containing C2S pastes increase in degree of hydration at 90 days by 47% compared to neat C2S pastes. These results suggest that addition of inert nanoparticles could potentially promote earlier strength gain of C2S in cement, ameliorating a perceived deficiency in cement compositions which could contribute to sustainability in terms of lower CO2 emissions and lower energy use compared to traditional chemistries.