Real Options methods are currently used to assess investment projects considering: (1) the decision options that one can have along the development of the project, such as to expand it, or reduce it, or to abandon it, or to differ it, and (2) the uncertainty in some financial variables for the assessment of the economic investment. In these two regards, Real Options methods are superior to the traditional Net Present Value method. The purpose of the present paper is to establish the basis for Real Options modeling for decision making on design, inspection, maintenance, and decommissioning of offshore structures. The use of Real Options theory is sought in order to account for: (1) uncertainties in the financial variables involved in risk assessment based on expected costs, such as the economic consequences due to failure of a system; and (2) uncertainties associated with the resistance and loading of the structure for reliability assessment. An application of Real Options Theory is given in the paper for decision making on maintenance for an offshore structure. Cash flow from oil revenue is modeled as a stochastic process. Preventive and corrective maintenance is analyzed as a critical situation where the decision maker has the option to pay the costs of maintenance in order to obtain a benefit. Expressions are derived for the estimation of the value of the maintenance option; they are based on the derivation of the Black-Scholes equation for the evaluation of financial options. It is shown that the value of such project is equal to the sum of the net cash flow of the project (as with a Net Present Value evaluation) plus the value of the maintenance option. Projects with one and two decision times along the life of the structure are formulated and analyzed. Closed form solutions are obtained for such cases. An example is given in order to illustrate the differences between maintenance decisions using the Net Present Value and the Real Options method.