Biodiesel is a promising cleaner burning, less toxic and renewable energy carrier. It is made primarily by transesterification of refined vegetable oils, but biodiesel from these sources are becoming more expensive. Therefore, alternative raw materials are being evaluated, but a major difficulty in the production of biodiesel from these alternative feedstocks is the high concentrations of free fatty acids. This is mainly due to the saponification reaction which occurs with the most commonly used alkali catalysts. Therefore in this work a parameter screening of the esterification of oleic acid, a free fatty acid, with ethanol in the presence of the heterogeneous acid catalyst Amberlyst 15 wet ion exchange was conducted with the intent to produce biodiesel. The parameters screened were reaction temperature, catalyst amount and the ratio between moles of alcohol and moles of fatty acid while the reaction time was set to 6 h. It was found that higher temperature and catalyst amounts increased conversion; however, the ratio between moles of alcohol and moles of fatty acid that gave the highest final conversion was 1:1. The highest Biodiesel yield obtained was 53%. In addition a reuse test of the catalyst was in order to test its recyclability; however, the catalyst presented a reduction in its activity after a single use. (C) 2016 Elsevier Ltd. All rights reserved.