Although Spectral and Pseudospectral methods have been used in a wide range of optimal control applications, to date, most of the literature uses these methods in a non-robust sense without considering possible dynamic deviation (uncertainties) from the nominal model. This study applies a recent robust approach for spectral and pseudospectral methods to a wave energy converter, considering structured uncertainty in the dynamical system. The results show that the robust approach gives better worst-case performance than an equivalent non-robust approach. Additionally, when structured uncertainty is considered in the dynamical system, the results show that the absorbed energy, obtained with the robust approach, is always positive. Finally, the...