A Reset observer (ReO) is a novel sort of observer consisting of an integrator, and a reset law that resets the output of the integrator depending on a predefined switching condition. For SISO systems, the switching condition is defined in such a manner that the ReO is reset when the output estimation error and the reset term have different sign. However, the way to define the reset condition to deal with MIMO systems has not been analyzed previously. As contributions, we provide a formulation to handle ReO for MIMO systems, and an algorithm to compute its 2 gain for performance purposes. Additionally, the effectiveness of our proposed MIMO ReO is analyzed by simulations. (C) 2011 Elsevier Ltd. All rights reserved.