The recent development of two types of environmental friendly cementitious materials, magnesium oxychloride cement and magnesium phosphate cement, at HKUST are presented. Both of them can develop high strength without heat treatment under elevated temperature, i.e. the bonding of these cementitious materials can be achieved at low temperature through chemical reaction, as opposed to fusion or sintering at high temperature. The preparation process of the two cements can not only save a lot of energy but also emit no carbon dioxide. For magnesium oxychloride cement, our research includes parametric study of the formulation, strength development, water resistance, and also identification of phase composition in the cement paste. Magnesium phosphate cement is mainly applied as rapid repair material in civil engineering. In this paper, the formulation, mechanical properties and performance in patch repair of mortar specimen including strength, bond ability to old concrete substrate, volume stability are studied.