The energy consumption is increasing rapidly due to population growth, improved living standards and industrialisation. A significant amount of fossil fuels is consumed by the transportation sector, which causes the fast depletion of fossil fuels and environmental pollution. These problems can be overcome by using Biodiesel. This research work aims to reduce the NO<inf>x</inf> emission in diesel engines. The literature survey reveals that the use of a fuel additive reduces the emissions by oxygenating the fuel. Among oxygenates, ether proves to behave better than alcohols. Hence, for this present work, two different types of ethers were selected which were not used in earlier occasions. DGME (Diethylene Glycol Monomethyl Ether) and DGMB (Diethylene Glycol Monobutyl Ether) are the two additives selected from the ether group and used as additives with palm oil methyl ester (POME) biodiesel in various proportions and tested in a direct injection compression ignition engine which reduced the emissions. To start with, the engine was run with diesel and subsequently with biodiesel and with the additives. The performance tests were carried out in a single-cylinder, four-stroke, water-cooled engine with and without exhaust gas recirculation (EGR). This engine is coupled with eddy current dynamometer. The use of biodiesel in conventional diesel engines results in substantial reduction in emission of carbon monoxide, particulates and unburned hydrocarbons, but increases NO<inf>x</inf> emission. This review focuses on reduction of NO<inf>x</inf> emission. Combustion and performance analysis of the engine have also been evaluated. © 2017 Elsevier B.V., All rights reserved.