Orbit determination results are obtained for the GSAT-1 spacecraft launched by the Indian Space Research Organization using the first of its indigenously developed geosynchronous satellite launch vehicles. A description is given of the processes by which the mission operational ground-based orbit determination software estimated the satellite’s achieved transfer orbit state. A comparison has been made between the determined transfer orbit elements and the injection parameters calculated immediately after launch by the inertial navigation system. A Monte Carlo simulation method that was used to estimate the errors in the orbit computed using the inertial navigation system data has been assessed. After injection, a major portion of the satellite’s transfer orbit could not be tracked. To come to a definite conclusion of the achieved transfer orbit, investigations have been made using simulated tracking data and the actual tracking data of earlier, comparable, geostationary satellite missions. The orbit determination program used for the analyses is based on Cowell’s formulation, the Gauss‐Jackson numerical integration algorithm, and the batch weighted least-squares estimation technique. The performance of the tracking systems employed for the mission at Lake Cowichan, Canada; Fucino, Italy; Hassan, India; and Perth, Australia, has also been evaluated. Nomenclature AS =e ffective cross-sectional area normal to the sun, km 2 ,m 2 AV = spacecraft cross-sectional area projected normal to Va ,k m 2 ,m 2