The doping of diamond is still an interesting topic for the production of microelectronic devices. During the last years several doping elements were investigated to produce p- but also n-type diamond. The mainly investigated doping elements are boron, nitrogen, phosphorus and sulfur. Diamond deposition experiments showed that different elements influence diamond deposition (nucleation and growth) and diamond properties very differently. Thermodynamic calculations of the gas phase chemistry help to understand the mechanism taking place during the deposition. The diamond deposition results and thermodynamic data for the various doping elements will be compared.