In this report, we present the preliminary work developed for our research project for the APDC (\'Area Pr\'atica de Desenvolvimento Curricular) course. The main goal of this project is to develop a framework, on top of the Why3 tool, for the verification of effectful higher-order programs. We use defunctionalization as an intermediate transformation from higher-order OCaml implementations into first order ones. The target for our translation is WhyML, the Why3's programming language. We believe defunctionalization can be an interesting route for the automated verification of higher-order programs, since one can employ off-the-shelf automated program verifiers to prove the correctness of the generated first-order program. This report also serves to introduce the reader to the subject of deductive program verification and some of the tools and concepts used to prove higher order effectful programs.