The effect of CO 2 injection on initial strength increase and hardening of cement-fibre mix in a cement bonded particle board (CBPB) production was evaluated. Different cement contents, formation pressure and types of fibres were considered. The initial strength increase with CO 2 injection is so much faster than this caused by conventional hydration that the produced samples do not need additional curing before they can be stored. Similar strength and stiffness values as in conventional products on the market are gained with lower cement content for similar types of fibres. Visual inspection of board surfaces aged for 13 years in a harsh exterior environment as well as comparison of strength and stiffness values for these boards when new and after ageing, gives a very satisfying result. The combined effect of the above discussed gains results in markedly increased productivity at lower cost and lower environmental impacts than is possible in traditional CBPB production.