The micro- and nano-composites containing 2, 4 and 6 by wt% of B4C particles in aluminium are fabricated using stir and ultrasonic cavitation-assisted casting processes. The fabricated composites are characterized by using scanning electron microscopy, X-ray diffractometer. The dry sliding wear behaviour of the prepared composites are investigated by using pin on disc method at an applied load of 4, 8, 12, 16 N for pin temperatures of 100 and 200 °C. The wear study at room temperature is also carried out for comparison. The investigations indicate that the wear resistance of the nano particle-reinforced composites are better than those of the micro B4C particle-reinforced composites under all loads and different temperatures. Analysis of wear surface and debris by scanning electron microscopy with energy dispersive X-ray diffractometer reveals the nature of wear mode of samples. It is also observed that the predominant wear mechanism for pure aluminium at 100 and 200 °C are adhesion and metal flow respectively, whereas for fabricated composites abrasion, delamination and oxidation are the most dominant wear mechanisms. © 2016, The Indian Institute of Metals - IIM.