This paper presents an experimental study comparing the performance and emissions of a flex-fuel engine with three different fuels. Originally, three fuels would be tested, Hydrous Ethanol (H100) and a mixture of 50 per cent Gasoline 50 per cent Anhydrous Ethanol (E50), Gasoline C (E25). However problems with the electronic control unit, provided by the engines manufacturer, prevented tests with the last two fuels from happening before the dead line date to deliver this work. So, only results with the fuel Hydrous Ethanol were obtained. Nevertheless it is presented a study of Gasoline and Ethanol fuel. The parameters for comparisons were the effective power, the fuel consumption, the specific fuel consumption, effective thermal efficiency and emissions of an Otto cycle engine. Tests were conducted with five different engine speeds, the higher being 3500 rpm. The results of performance and emissions were considered satisfactory, allowing constructive conclusions about the advantages of the fuel tested. At the end of this work, it is presented a comparison of cost R$/Liter by power generated (kW). This required a projection of what would be the price at the pump for the consumer of the fuel E50, as it is not commercially available. Different fuels may have better results in different operating condition. Moreover, these benefits may vary in other multifuel engine, so it is recommended for future work, testing different engines or even experiments with vehicle.