Multivariable (MIMO) processes are commonly found in the industry. The coupling between the different loops makes the controller design difficult. To solve the problem of controlling these processes, MIMO proportional integral (PI) controller design methods have been found in the literature. In this paper, the review and the experimental application of MIMO PI controller tuning methods with linear matrix inequalities constraints are presented. The considered tuning methods are formulated as a non-convex optimization problem. Linearization of the concave part around a known point is performed using the concave-convex procedure. Frequency-domain process data are used to solve problems. The application of the methods is done in two different processes: temperature module and Peltier module.