Magnesium based hybrid composites with carbon fiber, SiC_p and in-situ Mg₂Si reinforcements have been prepared through squeeze infiltration technique. The results of the studies done on measurement of the coefficient of thermal expansion (CTE) after thermal cycling have been presented. In the present paper, an attempt has been made to characterize the micro-structural evolution and the plastic deformation behaviour of these hybrid composites in the as cast condition and after thermal cycling. Attempt has also been made to study the effect of thermal treatment on the thermal expansion behaviour of the AM50+Nd magnesium based hybrid composites in terms of CTE values. Composites containing Nd show lower values of CTE compared to the base alloy. Further creep compression tests were carried out on these composites. Composites consisting of rare earth element Nd show much better creep properties as compared to the base alloy matrix. Results of creep compression tests carried out for some other Mg and Al base alloys and composites have also been included for comparison.