In order to protect rubberwood particle boards against moulds (Aspergillus sp and Trichothecium sp) and fungi (Gloeophylum sp. and Trametes sp.) application of essential oil (cinnamon or clove oil) as an antifungal agent was investigated. A solution of each essential oil in ethanol was sprayed onto rubberwood particles during a glue-particle blending process to achieve various concentrations of 0 to 3;(by mass of dried particles). Chemical compounds of essential oil deposited in the finished board after hot processing were investigated by gas chromatography-mass spectrometry analysis. Besides mould and decay resistance, physical and mechanical properties of the particle boards were examined. Cinnamaldehyde (1.8 mg g-1) and eugenol (5.2 mg g-1) were dected in boards treated with 3;cinnamon oil and clove oil respectively. A complete protection against growth of Aspergillus sp. and Trichothecium sp on the boards was extended from less than 1 week till 9 weeks at 25 degee C and 100;relative humidity. Percentage mass loss caused by Trametes sp. and Gloeophylum sp. was also reduced to 5;. Essential oil treatment reduced equilibrium moisture content and thickness swelling without affecting water absorption and bending properties of particleboards. Ineternal bond strength of particleboards remained unaffected by addition of cinnamon oil and clove oil up to 1.8;, above which s sl;ight reduction was observed.