The use of scanning transmission X-ray microscopy for the real-time study of cement hydration is presented. The technique is illustrated with a study of the hydration of tricalcium silicate. Tubules emerging from C3S grains were found to grow in a contorted fashion when the water-to-cement ratio was 3:1. This is in contrast to observations with larger water-to-cement ratios when the tubules were found to grow in a linear fashion. A scheme for the progression of the hydration reaction suggested by our observations is presented. The potential of chemical-state imaging was also explored and promises exciting possibilities for the understanding of cement hydration.