Partial oxidation (POX) is a type of chemical reaction. It occurs when a substoichiometric fuel-air mixture is partially combusted in a reformer, creating a hydrogen-rich syngas which can then be put to further use, for example in a fuel cell. A distinction is made between thermal partial oxidation (TPOX) and catalytic partial oxidation (CPOX).
- General reaction equation (without catalyst, TPOX): 
- General reaction equation (with catalyst, CPOX):
- Possible reaction equation (heating oil):
- Possible reaction equation (coal):
The formulas given for coal and heating oil show only a typical representative of these highly complex mixtures. Water is added to the process for getting both the extreme temperatures as well as extra control on the formation of soot.
The choice of reforming technique depends on the sulfur content of the fuel being used. CPOX can be employed if the sulfur content is below 50 ppm. A higher sulfur content can poison the catalyst, so the TPOX procedure is used for such fuels. However, recent research shows that CPOX is possible with sulfur contents up to 400ppm.
See also 
- Hydrogen production
- IPOX (indirect partial oxidation)
- Glossary of fuel cell terms
- Timeline of hydrogen technologies
- Rostrup-Nielsen, "Syngas in perspective", Catalysis Today 71 (2002), pp. 243-247.
- Electricity from wood through the combination of gasification and solid oxide fuel cells, Ph.D. Thesis by Florian Nagel, Swiss Federal Institute of Technology Zurich, 2008
- Industrial Gas Handbook, Frank G. Kerry, p. 230.
- This article incorporates information from