The autocovariance prediction method has been used for ionospheric forecasting of f0F2 values for 1, 2, 4, 8, and 12 hours ahead at a single location. Time series of f0F2 data for ionospheric quiet and disturbed conditions for February 1986 and September and December 1990 at different European stations were studied in order to clarify the forecasting capabilities of the method for ionospheric purposes. The accuracy of the method varies within reasonable limits depending on the time range of the forecast for different conditions. Samples of the results for representative periods are presented. The forecast is compared with observations, monthly median recommendations of the Radiocommunication Sector of the International Telecommunication Union (ITU-R), and persistence models. ¿ 2001 American Geophysical Union