The electrical conductivity of cement pastes can give an indication of the initial hydration of the cement pastes and early formation of products. In this study, sulphate-resisting cement (SRC) pastes were prepared with different doses of two synthesised admixtures, namely phenol formaldehyde sulphonate (PhFS) and melamine formaldehyde sulphonate (MFS). This work is aimed to evaluate the effect of PhFS and MFS on the hydration reaction of cement pastes during the first 24 h by determining the initial, final setting times and the electrical conductivity changes, as well as the effect of these polymers on the hydration progressing up to 90 days by determining the chemically combined water content and gel/space ratio of each paste at different intervals of time (1, 3, 7, 28 and 90 days).