This paper presents selected research results of the DFG founded project group, consisting of four institutes focusing on diagnostic methods in thermal coating processes. This group is now working for three years on this topic. Utilizing newest or self invented diagnostic devices, it became possible to describe plasma energy fields, particle feeding and plasma/particle interactions. This goal could be achieved by using the enthalpy probe and streak technique for describing the plasma state combined with results of the particle diagnostics, using the DPV2000 system, a newly invented Particle-Shape-Imaging device (PSI) and Particle Image Velocimetry (PIV). Moreover substrate diagnostics is achieved by using pyrometry and thermography techniques. Paper text in German.