This paper develops a design procedure of a MIMO PID (Multi-Input-Multi- Out.put Proportional-Integral-Derivative) control system for controlling level and temperature in a water tank plant. Such a plant can be described by interconnected nonlinear differential equations, which could complicate the analytical aspects of modeling and controller design. However, a linearized technic was applied to obtain a MIMO linear description, which permit to configure a control system by combining a linear MIMO PID controller acting on the water tank plant. Experimental results demonstrate that the designed controller is able to stabilize tank level and temperature simultaneously. The control software was written in LabVIEW code. Copyright © 2008 by the International Institute of Informatics and Systemics.