In this work, CoMn spinel (MnCo2O4+delta) was prepared from CoMn LDH and was applied as a catalyst toward toluene pyrolysis. Spinel samples with different degrees of crystallinity were evaluated by isothermal and stepwise heating experiments, as well as feeding toluene with different concentrations. Especially for the spinel with high degree of crystallinity, results exhibited a relatively low pyrolysis temperature of 400 degrees C, a high toluene conversion rate of similar to 100%, a large H-2 production and an acceptable benzene formation. More importantly, by various characterization techniques, an invisible active site was detected and believed to be formed by the reaction of CoMn spinel with toluene, and was designated as manganosite-cobalt nanoparticles supported on carbon nanotubes (MnO-Co/CNTs), which significantly promoted the degradation and carbonization reactions in the low temperature pyrolysis of toluene. (C) 2020 Elsevier Inc. All rights reserved.