Compressive flow behavior of hot-rolled (64% reduction in thickness) Al and Al-15% B4C composite was studied over the temperature and strain rate ranges of 25-500 °C and 10-4-1 s-1, respectively, in longitudinal (LT) and transverse (TD) directions. It was found that athermal region (i.e. temperature-independent region) in aluminum becomes less prominent upon reinforcing with 15% B4C particulates. The apparent stress exponent n' was found to vary between 10 to 30. It was also found that the stress exponent values could reduce to n = 5 upon subtracting the threshold stress from applied stress. Microstructural variation in aluminum was studied by EBSD and correlated with its flow behavior. © QinetiQ Ltd 2013.