Development of particleboard made from non-wood lignocellulose materials and natural adhesives has become intense research due to the decreased wood supply and fossil resource reserves. In this study, coconut husk and citric acid were used as the raw material and natural adhesive, respectively, for the experimental manufacture of particleboards. The effect of particles size and citric acid content on the physical properties of the particleboards were investigated. The particles sizes of coconut husk were divided into 3 sizes of mesh such as 4, 10, and 14. The boards were manufactured under the pressing conditions of 200 °C for 10 min. The citric acid content was varied in the range of 15 to 25 wt%. The board size and target density were 300 x 300 x 9 mm and 0.8 g/cm³, respectively. The physical properties of boards improved with small size of particles till 14 mesh and increasing of citric acid content reach to 20 wt%. The physical properties of boards used 14 mesh of particles and bonded with 25 wt% citric acid satisfied the requirement of the JIS A 5908 (2003) 18 type. Consequently, it was concluded that 14 mesh of the particles size and a citric acid content of 25 wt% were effective in manufacturing particleboards composed of coconut husk and citric acid.