Satellite positioning signal ionospheric delay has been identified as a single major contributor in total satellite positioning error budget. Daily dynamics of ionospheric delay are described globally by utilising the GPS standard (Klobuchar) ionospheric model. In this doctoral thesis, a regional ionospheric delay correction model has been proposed. The model is based on observed daily pattern ionospheric delay non-specific regularities, which are occuring under specified conditions; during quiet space weather, undisturbed ionosphere, in summer months period and at middle geographic latitudes. The local ionospheric delay dynamics are the reason and a motivation for conducted research, which was carried out aiming at GNSS services improvement and system performance. The model is developed on the basis of measured values of ionospheric delay. These values were derived from code and phase pseudorange observables from Adriatic region reference IGS stations. The model has been verified in time periods where defined conditions of satellite positioning signal propagation environment were prevailing. Obtained values were compared with actual ionospheric delay values, as well as with ionospheric delay values obtained with the Klobuchar ionospheric correction model. The proposed model has been tested in three different locations in the Adriatic region, in years 2006 and 2007. The results showed that, under specified conditions and controlling parameters, proposed ionospheric model provides more accurate ionospheric delay corrections compared to the Klobuchar model. The proposed model's applicability in the Adriatic region and surrounding has been confirmed. Model properties have been discussed from the accomplishment, advantages and limitations aspect. The potential of the model's scientific and practical appliance is presented, along with thesis research results. A model error analysis and error causes will set guidelines for further research activities regarding local and global ionospheric dynamics conditions, as well as solar and geomagnetic activity exploration.