Time-delays (dead time) are found in many processes in industrial practice. Time-delays are mainly caused by the time required to transport mass, energy and information. In many cases time-delay is caused by the effect produced by the accumulation of a large number of low-order systems. One of possibilities of control of such processes is their approximation by lower-order model with time-delay. The contribution is focused on the design of an algorithm for digital control of high order process that is approximated by a second-order model with time-delay. The controller algorithms use the digital modification of the linear quadratic (LQ) Smith predictor (SP). The LQ criterion was combined with pole assignment principle. These algorithms were applied to the control of a set of equal liquid cylinder atmospheric tanks.