Steam injection has become commercially available thermal enhanced oil recovery methods for recovering heavy crudes. Recently, there has been increase in research interest in in-situ catalytic upgrading. In this work, experimental investigations on the application of a new submicron dispersed trimetallic catalyst based on Ni-Co-Mo for enhanced recovery and upgrading of Omani heavy crude oil was conducted. The catalysis effect of the ultra-dispersed Ni-Co-Mo metals generated in-situ from water-in-oil emulsion was studied in the presence of sand packed bed as a porous medium in a steam simulation process. The results from the recovery tests showed a higher oil recovery (15% OOIP) in the presence of the catalyst than base steam injection case. Substantial improvement in quality of produced oil was observed as there was a tremendous reduction in oil's viscosity of about 25% with significant reduction in sulfur (26%), and increase in API gravity (10%). This enhancement of the quality of Produced liquids in terms of increase in API gravity, viscosity and sulfur reduction, is an indication of successful in situ upgrading of the oil. Analysis of solid and gaseous products recovered from the experimental runs conducted with the catalyst showed thermal expansion and viscosity reduction due to catalytic hydrocracking as the dominant mechanisms for oil recovery.