Air pollution from the large-scale combustion of fossil fuels has prompted researchers to look for alternatives. A viable alternative to the use of petroleum diesel must be technically possible, commercially viable, environmentally friendly, and affordable. Through a variety of techniques, biodiesel can be produced from renewable and low-grade sources, and it has the potential to become a viable alternative energy source. Cost-effective and environmentally friendly catalysts are expected to be frequently used in the biodiesel production process for the transesterification of several feedstocks. There have been several investigations into the conversion of the oil into biodiesel by homogeneous/heterogeneous catalysis and new heterogeneous catalysts are constantly being tested. Separation and leaching in harsh reaction conditions are two of the many challenges associated with the employment of homogeneous and heterogeneous catalysts respectively. Because of its great efficiency, researchers are increasingly interested in applying nano-catalysts for the generation of biodiesel. The development of nano-catalyst applications is the primary factor driving this growth. A review of several nano-catalysts utilized for biodiesel production from different feedstocks, as well as an evaluation of the major operational variables that influence biodiesel production and the accompanying obstacles in the transesterification process, are presented in this article. © 2022 Elsevier Inc. All rights reserved.