Elemental composition of biodiesel is required for product quality-control, auto-engine life, emissions control, and researching appropriate additives. The use of microwave assisted acid digestion reaction system to prepare neat biodiesel (B100) samples in an aqueous medium for simultaneous inductively coupled plasma optical emission spectrometer (ICP-OES) analyses is reported. Biodiesel produced by transesterification reaction was subjected to the test method using calibration standards prepared in an aqueous medium. Significant correlation for the spiked B100 samples, instrument detection limits, accuracy, and precision data showed that elemental concentrations can easily be determined within the specified limits. The method avoids switching any of the ICP-OES accessories required for high organic loads. This method is most appropriately devised for biodiesel analysis than petrochemicals analysis.