This paper investigates the performance of W-Ni-Cu heavy alloy with 0.5, 1.0, 1.5 and 2.0 wt% of cobalt addition. The alloys are prepared through spark plasma sintering (SPS) at a sintering temperature of 1400°C following a heating step of 100°C/min. The alloy with 0. 5 wt% cobalt is observed to have good mechanical properties in comparison with other alloys. The density and hardness of the alloys follow a decreasing trend with an increase in cobalt addition. Subsequently, the microstructural characteristics such as contiguity, average grain size and matrix volume fraction are measured and investigated, as they are found to affect the mechanical properties of the alloys. The average grain growth of the alloys varies around 13 µm. As the cobalt percentage is increased, W-W contiguity is observed to increase. The W-Ni-Cu-0.5Co alloy exhibits higher yield and tensile strength in comparison with other heavy tungsten alloys. The fracture surface analysis showed predominantly tungsten grain cleavage fracture for 0.5 wt% Co alloy. The other alloys showed more features of matrix interface failure and tungsten decohesion. © 2019 ICE Publishing: All rights reserved.