The stress rupture properties of 0.2 wt% Ni activated sintered W were studied using direct load tester at 1000℃, 1100℃ and 1200℃ in H₂. The stress rupture strength of 4 hr sintered specimen was 60% higher than that of 1 hr sintered specimen because of the larger grain size and the higher relative density. As the temperature increased from 1000℃ to 1100℃, rupture time was decreased but the slope of stress vs rupture time was decreased due to the grain growth at the higher temperature. The activation energy for the stress rupture was determined as 75 Kcal/mole. That was about the same energy for the diffusion of W in Ni. Therefore it was postulated that the deformation was controlled by the diffusion of W in the Ni rich area between the grains. All of the specimens showed intergranular fracture owing to the grain boundary sliding.