The effects of main veins of palm (Elaeis guineensis) particles and the amount of CaCl2 on the mechanical and physical properties of cement-bonded composite boards (CBCBs) were investigated in this study. Homogenous CBCBs were produced with main veins palm particles content at three levels of 10, 15, or 20 wt.% and CaCl2 at three levels of 0, 3, or 6 wt.%. Other manufacturing parameters consisting of pressure and time for cold-press, material dry weight, and panel dimensions were kept constant. The flexural strength, flexural modulus, internal bonding, water absorption, thickness swelling, and the thickness of CBCBs after 2 and 24 h immersion in distilled water were determined. The results indicated that increased amount of lignocellulosic particles caused a decrease in the mechanical properties of the CBCBs. The increase in calcium chloride up to 6 wt.% improved mechanical properties of the CBCBs. The panels manufactured with 10 wt.% E. guineensis particles and 6 wt.% CaCl2 showed the most favorable physical and mechanical properties.