Thermal plasma processes play nowadays a key role in many industrial applications, such as powder densification and spheroidization, synthesis of nano-powders, treatment of waste materials and spraying of thin coatings. Although many of these applications have been fully implemented industrially for many decades, modelling plays an important factor in their continued development and improvement. 3-D simulation of the behaviour of commercial inductively coupled (RF) plasma can be useful tool to predict the main features of plasma assisted treating and processing of injected raw materials. The effects of changing coil current frequency, the hydrogen mixing in argon primary gas and the flow patterns and temperature distributions have been investigated. 3-D time-dependent modelling DC non-transferred arc plasma torch for plasma spraying operating at atmospheric pressure can allow the prediction of particle trajectories and thermal history, the analysis of the influence of the plasma jet cold gas entrained eddies on particle behaviour and the mechanisms that can lead to a fluctuating and non homogeneous heating of the particle stream. All computations have been performed using a customized version of the CFD commercial code FLUENT©.