With the present work the basis for characterisation and optimization of the slit nozzle principle was provided. Basically the atomizing system is used for producing metal powders, for instance tin, aluminium and different nonferrous alloys. The first part of the thesis gives a survey of the state of the art according to different spraying systems. The main scientific approach to characterise and optimize a two-fluid nozzle, first in a model plant and afterwards in large-scale production is using dimensional analysis. In the theoretical chapters the application of the We-number, the Oh-number and the Re-number to describe the disintegration of a liquid sheet is pointed out. Subsequently an introduction of the currently used approach is given. Statistical design of experiments, gaining a model to describe the influence of different parameters on the atomizing result is used to solve the existing task. The experiments started on a water model plant by laserspectrometric measurement of the spraying cone. The main parameters influencing the atomizing result are the gas pressure and the geometrical settings of the nozzle. The target was to optimize the main grain size (d50) as well as the specific gas consumption. In the second part of the experimental description an additional gas stream, called secondary flow and its impact on the spraying result was analysed. Furthermore a CFD-simulation was applied to describe flow condition in the nozzles region. Although only the gas stream was considered in the simulation, a comparison between the practical results on the water model and the calculated ones showed that the CFD-simulation is an appropriate instrument for the optimization of the given atomizing system. After the detailed experimental study on the model plant, first preliminary experiments on a pilot plant were done. The tests showed that the parameters chosen in the water experiments could be transferred to produce tin powders as well as other low-melting alloys. It can be concluded that under the investigated conditions the process runs in a stable way and a saleable product is achieved.