Multiwalled carbon nanotube (MWCNT)-templated cobalt phthalocyanine (CoPc) assemblies are prepared by microwave reaction with the aid of NH4Cl. The assemblies of CoPc/MWCNTs are added to the electrolyte of Li/SOCl2 battery to show their potential application in the field of catalysis. The assemblies display a uniform coaxial nanotube structure. In the control test, the CoPc/MWCNTs synthesized without NH4Cl exhibit the aggregation of the nanotubes of CoPc/MWCNTs. It indicates that the use of NH4Cl as gas source is efficient in enhancing diffusion of the MWCNTs and controlling the growth of CoPc. The catalytic reduction of SOCl2 can be carried out by CoPc molecules outside the assemblies and the MWCNTs inside the assemblies. The assemblies of CoPc/ MWCNTs exhibit excellent electrochemical catalytic activity to Li/SOCl2 battery. The discharge energy of Li/SOCl2 battery catalyzed by CoPc/MWCNTs is 144% higher than that of the battery without catalyst, and is 94% higher than the energy of Li/SOCl2 battery catalyzed by bulk CoPc.