Upgrading of bitumen blended with microalgae Chlorella vulgaris was investigated in supercritical water (SCW) at 440 degrees C and 30 MPa in a home-made batch type bomb reactor. The effects of the water/feed ratio ranging from 2 to 10 and the effects of microalgae fraction in the feeds ranging from 0 (pure bitumen) to 100 wt.% (pure microalgae) were investigated. Pyrolysis experiments in the absence of water were also performed at the same conditions. SCW was found to suppress the coke formation. 25 wt.% microalgae addition to bitumen increased VR conversion 20% with a considerable increase in gas content and diesel yield. Increasing microalgae fraction in the feed to 50 wt.% resulted in increased light liquid yields due to increasing conversion of VR and also led to undesired increases in coke and gas formation. Water/feed ratio of 10 led to increased gas yields with a lower VR conversion.