Differential strain rate compression tests were conducted to study flow behavior of hot rolled Al-5wt% B4C composite as a function of sample orientation (longitudinal and transverse) over the temperature and strain rate ranges of 25-500°C and 10-4 to 1s-1, respectively. The longitudinal samples are found to show lower flow stress than that shown by the transverse samples in the temperature range of 25-200°C. The reverse becomes true at higher temperatures of 300-500°C. The values of stress exponent (n) and activation energy for deformation (Q), based on applied stress, ranged from 10 to 46 and 307-416kJ/mol, respectively. However, by considering effective stress, these values were reduced to n=8 and Q=126-190kJ/mol. This stress exponent ofn=8 is further reduced to n=5 by considering substructural evolution, which suggests the dislocation climb creep mechanism to be favorable for deformation. © 2013 Elsevier Ltd.