This work focuses on the solvent extraction and chemical modification of Azadirachta Indica seed oil (AISO) into a novel bio-based transformer insulating fluid. The effects of temperature, time and particle size on the AISO yield were studied. Extraction kinetics and thermodynamics were also investigated. The AISO batch was sequentially subjected to transesterification and epoxidation-esterification treatments to evaluate product quality after each stage. The vital operational characteristics of the modified Azadirachta Indica seed oil (MAISO) were determined. The AISO yield of 54.14 % was obtained at 55 °C, 150 min and 0.5 mm particle size. For the solvent extraction, pseudo second order, hyperbolic, Elovich’s and parabolic diffusion models all described the process kinetics, while Gibbs free energy, entropy and enthalpy values evaluated at 0.5 mm particle size were – 168.63 kJ/mol, 1.82 kJ/mol, and 428.11 kJ/mol, respectively. MAISO characteristics obtained for epoxidation-esterification were better than that of transesterification. The final MAISO characteristics after epoxidation-esterification are: -9 °C, 179 °C, 818 Kg/dm3, 1.66 mm2/s, 0.25 mgKOH/g, 0.11 mg/Kg and 52.86 KV for pour point, flash point, density, viscosity, acid value, moisture content and dielectric strength, respectively. The dissolved gas analysis result (in ppm) of the key gases for MAISO obtained after epoxidation-esterification are: <5, 67, 1624, 4, 7, 21, 4, <0.5 for H2, H2O, CO2, CO, C2H4, C2H6, CH4, C2H2, respectively. The characteristics met acceptable standard limits. MAISO properties (from transesterification and epoxidation-esterification) indicated its potential as substitute for mineral transformer fluid.