Abstract Present approach should find a potential application in preparing ternary alloy nanoparticles as a catalyst. Ternary Co–Ni–Cu nanocrystals (TMNs) have been successfully synthesized via hydrazine reduction procession. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HR-TEM) were employed to study the structural features of the nanomaterials. The resulting material showed a homogeneous alloy structure with an average diameter of 16.4 nm. Good composition control and size distribution of Co–Ni–Cu nanocrystals are achieved. It’s catalytic activity was investigated on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellants (CSPs) using thermogravimetry (TG), TG coupled with differential scanning calorimetry (TG-DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + (Co–Ni–Cu) has also been investigated using isoconversional and model-fitting approaches which have been applied to data for isothermal TG decomposition. TMNs can enhance catalytic activity towards thermal decomposition of AP as compared to Co–Ni and Ni–Cu bimetallic nanoparticles. The ignition delays and activation energies are found to decrease when TMNs were incorporated in the system. The burning rate of CSPs was considerably enhanced by these nanocrystals.