Over time, humanity has developed a greater reliance inpower generation, used to promoter comfort, transport and others. In order to address this increased demand new efficient sources are being searched, in preference, renewable sources. Transportation is one of the activities that have greater reliance on fossil fuels as well as being one of the largest generators of greenhouse gases. Therefore, in many parts of the world men are engaged in the search of new renewable energy sources that can substitute the current one used in transport. It is known that diesel engines are more efficient in comparison to the Otto engime. Due to this fact, for more than 30 years research has been conducted in order to develop ignition systems by compression, powered with renewable fuels, which reduces the dependence on fossil fuels and the emission of greenhouse gases. Ethanol is a viable candidate to replace diesel oil, but some improvements have to be accounted for before it s used in diesel engines, improvements such as the increase in compression ratio, adding auto-ignition improves, etc. Based on the facts presented, this thesis offers a new proposal, the use of n-butanol as an auto-ignition improver for ethanol. For this purpose several tests have been executed with various compression ratios, mass percentage of additive in the mixture off ethanol and many start of injections. The tests were performed in a rapid compression machine (RCM) with mixtures of ethanol and polyethylene glycol 400 and 600, and n-butanol inaddition to the reference test with diesel oil and ED95. The results show that n-butanol with a 10 per cent share of the mixture, can be used as an auto ignition improver for ethanol in compression ignition systems.