Diesel engines are well known for their high efficiency and durability. At the same time they are considered to be one of the largest contributors to environmental pollution. It is mainly due to their exhaust emissions. These exhaust emissions are responsible for many health issues to man and environment. The polluted climate change has forces the researchers to find the alternative, less carbon fuel. This paper aims at analyzing the emission characteristics of spirulina biodiesel with single hole nozzle. Transesterification methods are used during biodiesel production. The biodiesel is tested in Four Stroke, single cylinder variable comparison engine (VCR). The rated speed of the engine is 1500rpm at different loads. © 2021 Elsevier B.V., All rights reserved.