This article describes the construction of the GEMTEC global empirical model of the total electron content in the ionosphere, which is designed for satellite radio navigation. The model is based on the total electron content maps from GPS system measurements. Input data filtration and compression were performed through the natural orthogonal functions expansion method. The suggested model provides more accurate ionospheric delay for compensation of the propagation of radio signals in comparison to the standard model recommended by the interface control document of GPS systems. (C) 2011 Elsevier Ltd. All rights reserved.