Within the project ‘Plant champion air purification’, a public-private cooperation within Topsector Horticulture and Starting materials, research was carried out by Wageningen University & Research BU Greenhouse Horticulture on the possibilities of plants to purify indoor contaminated air. In this report the experimental findings are reported. The general conclusion is that plants can effectively remove Volatile Organic Compounds (VOCs) without causing plant injury. Formaldehyde is research being a typical hydrophilic VOC, for the ornamental plants Ficus, Spathiphyllum, Sansevieria en Cyperus. Ficus is the fastest in removing formaldehyde from the air by its aboveground leaves. Incorporating also the substrate, then Cyperus is the fastest. It was shown that the presence of water in air and/or substrate is a key factor in the rate of formaldehyde depletion. The second VOC examined was the lipophylic xylene which followed an uptake pathway other than formaldehyde. In the experiments it was shown that xylene was adsorbed to the leaf only temporarily, and was again mostly reemitted when brought into clean air. Possibly the substrate is of bigger importance then the plant in removing xylene and other lipophilic VOC, as was also stated in literature. The research shows that plants clearly have the potential to purify the indoor air from VOC.