This paper summarizes the results of experimental studies in which the aluminum alloy AW7075-T651 was friction stir welded (FSW) using various combinations of process parameters (rotational - R and travel speed - T). Mechanical properties of the test welds were assessed by using static tensile test and Vickers hardness measurement. The temperature of the welded plates was monitored during welding by means of thermocouples placed on both sides of the joint line, 15 mm from the weld axis as well as by using thermo camera. The microstructure, chemical composition and phase identification of the welding joints were examined using optical and scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffractometry (XRD). Investigations revealed that the temperatures at the weld center can reach values close to 550 °C and raised with R/T ratio increasing. It was found that tensile strength of welded joints is not correlated with R/T ratio and averages about 60% to 80% of tensile strength of a base material AW7075-T651. XRD analysis demonstrated that there is also deformation texture in the nugget (WN) and the thermo-mechanical affected zone (TMAZ) with strong dependence on process parameters.