The effects of chemical composition and thermal cycling on the martensitic transformation characteristics in Cu-rich, equiatomic and Zr-rich CuZr binary alloys have been studied by calorimetry. Only martensite could be indentified in equiatomic Cu_(49.9)Zr_(50.1) alloy, while Cu_(10)Zr_7 and CuZr₂intermetallic compounds as well as martensite were formed by rapid cooling from the melts in Cu-rich Cu_(52.2)Zr_(47.5) alloy and Zr-rich Cu_(48.4)Zr_(51.6) alloy, respectively. The M_s temperature of Cu_(49.9)Zr_(50.1) was 156℃ but those of Cu_(52.5)Zr_(47.5) and Cu_(48.4)Zr_(51.6) alloys, being 109℃ and 138℃, were lower than that of equiatomic Cu_(49.9)Zr_(50.1) alloy. In all the alloys, the M_s temperature has fallen but the A_s temperature has risen, resulting in widening of the transformation hysteresis with thermal cycling. The anomalous characteristics in the transformation temperature are due to the presence of the intermetallic compounds i.e. Cu_(10)Zr_7 and CuZr₂formed by an eutectoid reaction during thermal cycling in the temperature range between -100℃