Cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD) are the most commonly applied techniques used for heavy oil (HO) and bitumen (B) recovery. However, these methods, especially CSS, suffer from low recovery factor and production of highly viscous oil that requires additional up-grading treatment for transportation. The objective of this dissertation is to overcome such problems by application of metal nano-particles as catalysts. During the steam stimulation process, a series of reactions, called aquathermolysis, occur among oil, water and reservoir matrix. These reactions tend to break down the complex and big organosulfur compounds in the asphaltene fraction of the HO/B by cleaving the C-S bonds. Catalyzing these reactions can provide significant upgrading of the oil at the temperature range of steam stimulation. This catalysis can be achieved by using transition metal nano-particles. In this research, nickel, which is commercially used in many catalysis processes in the industry, is used for this purpose. Initially, the interactions of the nickel nano-particles with oil and water at different temperatures are studied, and the effect of the concentration, size and type of the catalyst on the process is evaluated. Next, a methodology is proposed to efficiently stabilize and inject the metal nano-particles into heavy oil reservoirs for catalysis purpose. Also, the degree of catalysis of the aquathermolysis is determined by studying the kinetics of the aquathermolysis and catalytic aquathermolysis of heavy oil. Finally, the effect of this catalysis on the recovery factor of the model cyclic steam stimulation is studied experimentally. In addition to steam injection dominated by aquathermolysis reactions, the influence of the nickel ionic solution on the low temperature oxidation during in-situ combustion is studied through TGA-FTIR and kinetic analysis. It is concluded that the quality of the produced oil can be significantly improved by using the nickel nano-particles during steam stimulation or in-situ combustion. The recovery factor of the above mentioned recovery processes also increases due to decreasing oil viscosity in the reservoir by catalysis. This method can significantly improve the economics of the thermal heavy oil recovery projects and decrease the complexities of heavy oil transportation and ex-situ upgrading.