In this work, moisture curable flame retardant HTPB-based polyurethane adhesives were synthesized. The influence of HBCD (Hexabromocyclododecane) as flame retardant on adhesion, degradation and change in flammability of synthesized HTPB-based polyurethane has been studied. Relationship between phase separation in hard and soft domains and adhesion has also been investigated. FTIR analysis was used to determine phase separation in synthesized adhesives. Lap shear test,vas used to determine adhesion properties of adhesives applied on aluminum and glass substrates. Thermal Gravimetry analysis and Limited Oxygen Index (LOI) tests were carried out on flame retardant adhesives to evaluate effect of HBCD on degradation and flammability. Addition of HBCD to adhesives leads to reduction of thermal stability and lap shear strength for all substrates, in spite of flame retardant adhesives show higher LOI value. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 3-538-3543, 2008