The maximum permissible formaldehyde content for E1 quality particleboard is 8 mg CHOH/100 g dry particleboard sample according to EN 312 [18]. Particleboard types 2, 4, 8, 10 and 12 met the required level of FE for indoor applications. The hardener type, conditioning period, and urea usage significantly affected the FE of the particleboards. In particular, the incorporation of the urea into the UF resin significantly decreased the FE of the particleboards. This was good consistent with the previous studies [3] and [10]. The particleboards made with the ammonium chloride had the lowest FE, followed by the particleboards made with ammonium sulphate and aluminium sulphate, respectively.