Many in situ recovery methods have been developed to extract heavy oil and bitumen from deep reservoirs. The "underground refinery" approach using a nanosize ultradispersed (UD) catalyst is one of the alternatives to surface upgrading that may become the "next generation" of oil sands industry improvement. Water-in-vacuum gas oil microemulsions containing trimetallic (W, Ni, and Mo) ultradispersed colloidal nanoparticles could penetrate inside the porous medium and react with the bitumen. This study is aimed at developing a catalytic-enhanced oil recovery method for Athabasca bitumen recovery through the viscosity reduction mechanism with the aid of trimetallic nanoparticles. In this study, series of experiments were conducted at a pressure of 3.5 MPa, residence time of 36 h, and temperatures from 320 to 340 degrees C in an oil sands packed bed column. Results of three consecutive categories of hot fluid injection (in the presence or absence of trimetallic nanoparticles) are presented. For the first category, the obtained experimental results showed that the recovery curve for vacuum gas oil injection without nanocatalysts was at a plateau. In the second series of tests, observations proved that adding a certain percentage of pentane enhanced the recovery performance of injection tests. The third phase of experiments was conducted in the presence of trimetallic nanocatalysts in emulsion with vacuum gas oil. Results showed the effectiveness of nanocatalysts for enhancing the recovery performance compared with the cases of no nanoparticle implementation.