This study has identified a potential HTPB based propellant that gives a very good density specific impulse but yet does not burn like a solid propellant. Due to low solid loading in this propellant, pre-curing of the HTPB and IPDI mixture is a necessity to get uniform density across the length of the grain. Nearly 7 hours of pre-curing gave the best results in terms of uniformity of the propellant composition. The paper also discusses the enhancement of regression rate of this propellant with known burn rate modifiers like iron oxide and copper chromite. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.