The present work has objective to analyze the investiment of a XTL plant using the Real Options Theory. This methodology is adjusted to evaluate the capacity that this project has to changes its input and/or output, in other words, to elect the option that maximizes payoff, in accordance with each scenario, allowing to evaluate the construction of a plant with flexibilities with the investiments happening in an environment of economical and/or technical uncertainties, where the prices (uncertainty factors) are stochastic and will follow the Mean Reversion Model, calculated by the Monte Carlo Simulation. The XTL technology is divided in two stages: a gasification process followed by a GTL (gas-to-liquid) process. The gasification process allows you to transform solids, liquids and gases into synthesis gas, that will be used as input of the GTL. The GTL makes possible to transform the syntesis gas into high quality liquids, such as naphtha, diesel, paraffins and lubrificants. This work is part of a project, with the objective to apply the Real Options Theory in the evaluation of investiments in Research and Development (R&D), aiming to price and consider the flexibilities that are inherent to this project.