In this paper, the influence of precursors (CA, C₇A₃Z, C₁₂A₇, C₆SrA₃Z, C₇A₂FZ and commercial calcium aluminate cement ‘Gorkal 70’) on the structure, microstructure and thermal stability characterizations of C₃AH₆ through hydration was investigated. The materials were characterized by X-ray diffraction, differential thermal analysis–thermogravimetric analysis–evolved gas analysis and scanning electron microscopy combined with energy-dispersive spectroscopy 24 h and 72 h after starting the hydration process. Results of investigation confirmed the influence of precursor on shape and grain size of C₃AH₆. The CaO/Al₂O₃ mass ratio of precursors before the hydration process affects the size of C₃AH₆ crystals: the higher the CaO/Al₂O₃ value, the larger the size of the crystals of C₃AH₆. Moreover, the presence of Sr and Fe affects the formation of stable C₃AH₆ crystals.