In this paper, we study the interactions between a public body and several potential concession holders. We propose a dynamic stochastic optimization problem providing the optimal exercise price of the “expropriation” option, which safeguards the social interest from over-exploitation of the resource. Other crucial quantities are also determined, such as the optimal value of the option and the condition for mutual convenience to enter the deal. We apply the model to a Southern Italy oilfield finding that the deal was in the common interest and that the optimal expropriation value is quite high. •Concession contracts are a widespread tool for public and private partnership in the exploitation of natural resources.•The article models the interactions between a public body and several potential concession holders.•The model determines key variables in closed-form solutions that can be implemented in real world cases.•The model provides useful information also in renegotiations phases of concession contracts.•The article presents an application to an oilfiled located in the South of Italy.