The relationship between plasma properties and cutting performance for a plasma arc cutting system was investigated. Plasma properties such as temperature and composition were measured using spectroscopic techniques in a 200 amp oxygen plasma cutting system. In addition to the plasma properties, the symmetry of the cylindrical cutting arc was also quantified. Cutting performance was measured by analyzing the edge quality of sample cuts. The most important measure of edge quality for this study was the angle of the cut edge. Operating parameters investigated included the effect of shield gas flow and geometry changes caused by cathode erosion. The measured plasma properties are used to account for the observed increase in recommended cutting speed for different consumable designs which operated at the same current level. A strong correlation was also shown between the measured arc symmetry and the cutting performance.