To understand general ionosphere properties over Serbia, an analysis of temporal and spatial ionosphere Total Electron Content (TEC) over the region was performed.
The present research focuses on daily, seasonal and spatial ionosphere variations, based on TEC series calculated from the GNSS ie. GPS measurements. This analysis provides for characterization of ionosphere nature and fine structure over Serbia, both locally and regionally. For the days with high solar activity changes of TEC values ranges from minimum 4 Total Electron Content Units (TECU), in night hours, up to 55 TECU around the noon. It is shown that that changes are equivalent to the to the delay of GPS signals approximately 8.8 m in in vertical direction during the (maximum) daily conditions and the delay of 0.6 m during the (minimum) night conditions. Also, it is shows that a seasonal TEC differences follows directly Son activity during the seasons, and maximal differences of TEC values between the seasons reaching values of 45 TECU, again in the years of high Sun’s activities. For spatial changes all gained results indicate that there exist changes in all directions which cannot be
recognized as constant bias or a trend.

Key words: GNSS, GPS, Ionosphere Variation, Total Electron Content (TEC)