Neem seed oil and oil cake after oil extraction are available in plenty especially in tropical countries. A detailed study has been made on the preparation of Neem Oil Methyl Ester (NOME) biodiesel from Neem oil. The NOME oil was tested for different fuel properties as per standard test methods and its efficiency and emission in a constant speed direct injection diesel engine. The engine exhaust emissions such as carbon monoxide (CO), unburnt hydrocarbon (HC) are found substantially lower for the NOME oil compared to that of diesel fuel mode. Raw hides/skins are the raw material for the leather industry and they are preserved with large amounts of common salt and these salts are removed during leather processing which causes soil and groundwater pollution. To develop less salt preservation technology, the Neem oil cake after oil extraction along with the minimum quantity of salt has been used as a preservative for raw hides and skins. The skin preserved with this bio-additive salt combination has no adverse effect on the quality of final leather. There was a substantial decrease in TDS in the soak liquor effluent by this new method. These studies indicate that both Neem oil and oil cake can be used effectively in two major manufacturing industries, i.e., automobile and leather industry to minimize environmental degradation in air, soil and, water. © 2018, Nova Science Publishers, Inc.. All rights reserved.