The hot deformation behavior of sintered Al-4%B4C composites was studied in this work. The main aim of this work is to estimate the effect of initial relative density (IRD), deformation temperature and strain rate on the hot deformation behavior and development of constitutive equations for predicting the hot deformation behavior. For this purpose, upsetting was performed in a hydraulic press for obtaining true stress-true strain curve data of sintered Al-4%B4C composites. The tests were carried out at different IRDes of 80%, 85% and 90% for various temperatures of 573 K, 673 K and 773 K and strain rates of 0.1 s-1, 0.2 s-1 and 0.3 s-1. The test reveals that the effect of IRD, deformation temperature and strain rate on flow stress curves is significant. The constitutive equations have been developed for predicting the flow stress behavior during the hot upsetting of sintered Al-4%B4C composite and it's validated with experiments. In addition, the required activation energies (Q) of sintered Al-4%B4C composites during the hot upsetting were calculated for various IRDes of 80%, 85%, and 90% was 161.06, 172.28 and181.05 KJ/mol, respectively, which is higher than the value of pure aluminum (144.3 KJ mol-1). © 2020 IOP Publishing Ltd.