Vegetable oils are an effective alternative to mineral oil for power transformers due to their high biodegradability and excellent dielectric strength. Moreover, adding a small number of nanoparticles (NPs) to vegetable oils can cause a significant increase in the dielectric strength of vegetable oils. This paper presents an experimental study of the physical and electrical properties of Mustard oil and its titanium dioxide (TiO2) based nanofluids (NFs). Physical properties include viscosity, water content, specific gravity, acidic content, flash point, and pour point whereas electrical properties include the AC dielectric  strength and partial discharge analysis. All the properties were determined according to IEC/ISO standards. Nanofluids were  characterized using scanning electron microscopy and x-ray  dispersion analyzer. Titanium dioxide based nanofluids were added to pure Mustard oil in varying quantities of 0.02 g/liter,  0.05 g/liter, and 0.1 g/liter to make NFs. The experimental  results indicate that 0.05 g/L NF has best properties among all  the four samples, and it has the ability to substitute conventional  mineral oil. Experimental study showed that there was an  increase of 40% in AC dielectric strength, 3 times increase in the  partial discharge inception and extinction voltage when 0.05 g/L  TiO2 was added in Mineral oil as compared to the experimental  study of pure Mineral oil. The comparison of physical and  electrical properties of the said sample was compared with  mineral oil and other vegetable oils. It has been observed that 0.05 g/L TiO2 is also cost effective alternative to mineral oil and  other vegetable oils.