Goal of this study is to determine appropriate synthesis conditions for the formation of zirconium-oxy-carbo-nitride solid solutions (ZrX), which belong to the pseudo-ternary system „ZrO“-ZrN-ZrC. Zirconia and carbon black were used as basic raw materials. Process parameters (firing temperature, carbon content, dwell time, and atmosphere in the furnace) were altered. Firing temperatures changed from 1400°C to 1650°C with a dwell time of 1-6hrs. The basic raw material had a carbon content between 2,01m% and 15,00m%. Different samples were fired in various atmospheres - either in air, nitrogen gas or embedded in coke breeze. Furthermore, a distinction between an alumina furnace and a graphite furnace was made. After carbonitriding ZrO2 not only ZrX-phases were built, but also beta-type zirconium-oxy-nitride phases which belong to the system ZrO2-Zr3N4. ZrX- and beta-Phases can be used in ceramic products. In order to analyse the phases, which are formed during different conditions, reflected light microscopy and scanning electron microscopy (SEM) were carried out. The detected phases were determined by energy dispersive X-ray spectroscopy (EDX). X-ray diffraction (XRD) was used for detecting the semiquantitative amount of the formed phases in the samples. Finally, a simultaneous thermal analysis (STA) of selected products was conducted for stating the oxidation resistance of ZrX- and beta-phases. All tests have shown that large amounts of ZrX-phases are formed in an alumina furnace with nitrogen gas purging if the samples are embedded in coke breeze. The results depend on the carbon content of the samples before being embedded in coke breeze. In detail over 65% of ZrX-phases were synthesised with an initial carbon content of 15,00m%, a firing temperature of 1600°C, and a dwell time of 6hrs. By firing an unembedded green body in nitrogen gas, no ZrX was formed. Firing an embedded green body in air, no ZrX, but small amounts of beta-phases were synthesised. According to the STA the new material’s oxidation starts at ca. 500°C. However, it is not complete before reaching 1380°C.