The present escalating demand for the hydrocarbon fuel and its lack of availability move the automotive industries and the oil companies to urge the search for alternative resources and feedstocks to emerge a fuel for transportation to keep going. This paper deals with the examination of properties of the Tamarind seed Biodiesel and the petroleum diesel fuel with biodiesel oils of significant feedstocks. The raw oil extracted from Tamarind Seed was trans-esterified with methanol in the presence of potassium hydroxide to obtain biodiesel. The oil yield was 35%. The study was to figure out the variation in the physicochemical properties of the biodiesel for their progressive blend percentages with the petroleum diesel. The blends investigated were B20, B40, B60 and B80. The vital physicochemical properties of the biodiesel evaluated were flashpoint, fire point, kinematic viscosity, and the calorific value. Importantly, the calorific value of B100 is 45.83 MJ/Kg and diesel is 45.49 MJ/Kg. The increasing biodiesel concentrations show, the kinematic viscosity of the blended fuel decreases to 2.4 cSt at B80 from 2.63 cSt for Diesel, which is 13%. The flash and fire point value of the diesel fuel which is 37.4 and 56.7°C, was incremented with the higher concentrations of biodiesel as 41.2°C and 57.7°C at B80. © 2020 Elsevier B.V., All rights reserved.