The pH of colloids is an important electrokinetic property which determines phase stability. We report the effect of temperature and nanoparticle concentration on pH of different nanocolloids of nanomaterials of varied morphologies and sizes. Measurements over a temperature range show that the pH of nanocolloids is a strong function of temperature and the concentration of the dispersed phase. Charge transport mechanisms leading to changes in the effective proton population are discussed. The mannerism in which the electric double layer (EDL) at the particle-fluid interface affects the pH of nanocolloids is presented by appealing to the DLVO theory of electrokinetics dispersion. © 2017, Springer-Verlag GmbH Germany.