An in-house Fortran-based two-phase Eulerian–Eulerian solver is used to numerically study water-based and liquid metal gallium-based alumina-copper hybrid nanofluid forced convection flow through a wide rectangular mini channel in the laminar regime. The governing equations of liquid and solid phases are solved using sixth-order compact finite difference method. A parametric study involving Reynolds number, particle concentration and mixture ratios has been reported. From the study it is found that pure liquid gallium has 43.5% greater heat transfer enhancement compared to pure water. The ‘heat transfer performance parameter’ is used to analyze the heat transfer characteristics of all the nanofluids considered. Addition of copper nanoparticles into base fluid improves the heat transfer performance of liquid gallium by 10.73% and pure water by 46.9%, at 1% particle concentration and a Reynolds number of 100. A significant change in heat transfer performance is found with a change in the Reynolds number and particle concentration for water-based hybrid nanofluids compared to liquid gallium-based hybrid nanofluids. A Nusselt number correlation is proposed for alumina-copper water-based hybrid nanofluids. Present results are validated with numerical and experimental results available in the literature. © 2022 Taylor & Francis Group, LLC.