The main objective of this study is to provide an investment analysis of a crude oil refinery in Brazil, an oil products importer country, under the real option theory, an approach with great academic and practical use, allowing a fairer refinery valuation by modeling uncertainty and including managerial flexibility, neglected in traditional analysis. The uncertainties considered, described by stochastic process, are the exchange rate and the crack spread, adapting the crack spread to the Brazilian refining. The options to defer, to shut down and their interaction are analyzed. It is shown the best decision considering the remaining investment and how this decision would be changed if the project hadn t been started. Considering the remaining investment, the best decision is to defer the investment if it is an infinitely-lived option and invest immediately if the right to invest expires upon 5 years. The influence of volatility e convenience yield was also taken into account and shows different recommendations, reducing the results robustness. When the full investment is analyzed, postponement is recommended in all analyzed scenarios. The shutdown option increases the refinery value and reduces the option to defer value. The developed model allowed an improvement in the investment analysis of this refinery and can be replicated to other refineries investment analysis, owned by the same company or not. For further works, we propose to include the switch input-output option, improve the crack spread modeling and consider the gas price as uncertainty.