Elemental composition of biodiesel is required for product quality control, auto-engine life, emissions control, and researching appropriate additives. We studied the use of microwave assisted acid digestion reaction system to prepare neat biodiesel (B100) samples in an aqueous medium for ICP-OES analyses. Biodiesel produced by a transesterification reaction was subjected to the test method for metal and non-metal elemental analyses using calibration standards prepared in an aqueous solution. Significant correlation was evident when a series of B100 samples spiked with different concentrations of the elements were analyzed. Instrument detection limits (IDLs) showed that elemental concentrations can easily be determined within the limits specified for neat biodiesel. Accuracy and precision data indicated significance of the method. The method avoids switching any of the ICP-OES accessories required for high organic loads. Biodiesel was successfully tested alongside other environmental matrices without affecting sensitivity of the instrument.