The variation in microstructure of high power plasma sprayed nickel coatings deposited with particle velocities ranging from 150 to 425 m/s and nominal particle temperatures of 1650 or 2050°C has been characterized. The relative density of coatings produced at the higher temperature is above 99.5% of theoretical regardless of the particle velocity; at the lower particle temperature the relative density is found to increase with increasing particle velocity. The fraction of unmelted particles is also found to increase with increasing velocity at the lower temperature. The relative deposition efficiency is approximately twice as high for the lower temperature particles compared to the high temperature, and for both temperatures the deposition efficiency decreases substantially with increasing velocity. Changes in the morphology of individual splats with changes in particle characteristics are also described.