AbstractMg-Ca-Gd based alloys are investigated as a potential alloy for degradable biomaterials with some promising results. In this investigation the Mg10CaxGd (x=5, 10, 20) were investigated with synchrotron radiation X-ray diffraction during solidification to follow the phase evolution at two different cooling rates at 5 and 50 K min-1. All three alloys show formation of α -Mg followed by Mg2Ca phase, while only Mg10Ca20Gd alloy contained Mg5Gd phase during solidification. During cooling α -Mg was first observed between 628 and 632°C at a cooling rate of 5 K min-1 while this decreased to 620-628°C with the increase in cooling rate to 50 K min-1. The change in cooling rate from 5 to 50 K min-1 did not change the types of intermetallic phases observed but resulted in suppressing temperatures at which the intermetallic phases were first detected.