Monolithic energetic gels were prepared in acetone by separately cross-linking the single precursors, glycidyl azide polyol (GAP polyol polyol), nitrocellulose (NC, 12% N), and tris(hydroxymethyl)nitromethane (THMNM) and the mixed precursors (GAP polyol + NC) and (GAP polyol + THMNM) with hexamethylene iisocyanate (HDI). THMNM functions as a chain extender. The synthesis conditions were optimized according to precursor mass ratio, cross-linking agent, solvent, catalyst concentration, and containers with various surface-to-volume ratios. The concentrations of reactants and cure catalyst are the most important factors. The composite energetic materials with a high degree of homogeneity were synthesized by trapping hexanitrohexazaisowurtzitane (CL-20) on the nano scale in the energetic polymer gels using sol get processing with a modified freeze-drying procedure. Loadings up to 85%, 93%, and 90% by weight of CL-20 yielded, respectively, monolithic gels for GAP/HDI, NC/HDI, and THMNM/HDI. 90% CL-20 can be loaded into gels of the mixed precursors of (GAP polyol + NC) and (GAP polyol + THMNM). The energetic gets and composites were characterized using FT-IR spectroscopy, DSC, SEM, and sensitivity to drop weight impact. The sensitivity of CL-20 is reduced in the energetic nanocomposites.