Nanotransformer oil is a type of nanofluid in which nanomaterial is mixed with transformer oil as a base fluid. Nanotransformer oil has potential of better heat transfer characteristics as compared to conventional transformer oils used for cooling purposes. Thermal conductivity and viscosity are the important thermophysical properties of any nanofluid which affect its heat transfer performance. In this study, an experimental attempt has been made to know about thermal conductivity and viscosity of nano-transformer oil. Experiments have been conducted at different temperature (200-500 C) and with varying volume concentrations (0.1%, 0.3% & 0.5%) of nanoparticles in the transformer oil. Research is already going on where researchers are using either water or ethylene glycol as base fluid. A very limited investigation have been reported for the transformer oil as a base fluid. Here attempt has been made to investigate the nanomaterial based transformer oil, called nanotransformer oil.