The present article contributes to a detailed study of the influence of copper (I) heteroleptic complexes on the thermal stability of ammonium perchlorate (AP). The studied complexes (C1-C4) are based on ethane-1,2-diimine analogues and biphosphines. The complexes C1-C4 were synthesised and characterised by NMR, HRMS, and, in the case of C1 and C3, X-ray diffraction. The effect of C1-C4 on the thermal stability of AP was studied by differential scanning calorimetry technique. These results show that the compound C4 increased the AP maximum exothermic peak from 415 degrees C to 432 degrees C and decreased the heat released from 1093 J g-1 to 414 J g1 complexes and the reported compounds. , exhibiting the higher retardant effect on the thermal decomposition of AP, in contrast to the other evaluated