The aim of this work is to investigate how to establish a 2-d observer based control system under the disturbance attenuation constraint. The model of the system to be controlled is endowed with components carrying past information, which in the ordinary 1-d control systems correspond to the delays. This fact makes the work unique in the sense that reports on this issue are still not available in the literature, to the best of author's knowledge. In this paper, we adopt the Lyapunov method approach and furthermore make use of the linear matrix inequality (LMI) formalism to put the results in the computational context. Thus, the energy function introduced will play the key role in this study