Plant oil as household energy Could be a sustainable and locally available alternative for fossil fuel. However, the use of pure plant oil in pressure stoves leads to deposit in the vaporizer. Therefore, objective of this study was to investigate the effect of the degree of unsaturation of plant oils on performance and deposit formation. Soybean oil with an iodine value of 128 g l(2)/100 g was used as well as partly hydrogenated soybean oil with an iodine value of 62 g l(2)/100 g, hydrogenated soybean oil with an iodine value of 1 g l(2)/100 g, and a blend of 50% refined soybean oil and 50% partly hydrogenated soybean oil was confected to obtain an iodine value of 95 g l(2)/100 g. In burning trials, the specific fuel consumption, the required frequency of nozzle cleaning and the amount of deposit in the vaporizer were measured. Results showed an exponential increase of deposits in the vaporizer when iodine value of soybean oil was increased: deposits amounted to 0.26 g/kg of consumed fuel for hydrogenated soybean oil and 0.70 g/kg for the original (untreated) soybean oil. However, an increase in the soybean oil iodine value did not affect fuel consumption, which was 0.296 kg/h for hydrogenated soybean oil compared to 0.286 kg/h for original (untreated) soybean oil. Further research is necessary to investigate the chemical reactions in the vaporizer to identify key precursors (factors) and reactions mechanisms that could influence the formation of deposits in plant oil pressure stoves. (C) 2009 Elsevier Ltd. All rights reserved.