The limited work has been done so far using neat biodiesel in the diesel engine since it drastically reduces the brake thermal efficiency (BTE) and emitting higher amount of oxides of nitrogen (NOx). Hence in the present investigation an attempt has been made to use neat biodiesels in DI diesel engine on par with diesel fuel with some alternate methods that have to be incorporated to improve the efficiency and to reduce NOx emission. The biodiesels used for the present investigation are nerium, mahua and calophyllum and these biodiesels are easily available and very cheaper when compared to that of other biodiesels. The catalyst coated combustion is created by using catalyst ZrO2 and used to improve the performance of the engine. Further, the antioxidant additive L-ascorbic acid can contribute towards fuel economy and emissions reduction either directly or indirectly in the diesel engine. The experiments were conducted in a single cylinder four stroke diesel engine to find the performance and emission characteristics using neat biodiesels with ZrO2 coated piston and L-ascorbic acid of 200 mg. From the experimental investigations, it has been found that ZrO2 coated piston with nerium biodiesel and along with L-ascorbic acid of 200 mg showed better results, which is very closer to diesel when compared in all aspects.