Composite solid propellants based on ammonium perchlorate/hydroxyterminated polybutadiene/isophorone dyisocyanate including different contents of octogene (HMX) have been represented in this paper. The mass of HMX increased in relation to oxidant, with constant bimodal fraction ratio. Combustion of the propellants has been improved by adding of titanium (IV) oxide powder as stabilizer. Parameters of burning rate laws were determined and compared for the propellants of the same total solid phase. Also, the apparent viscosity, uniaxial mechanical characteristic, density and energetic values were determined for the same formulations.