© 2019 Elsevier B.V. Activity of calcined scallop shell (CSS) for the catalytic pyrolysis of wasted fishing net (WFN) to the ε-caprolactam monomer was investigated in a micro-furnace type temperature programmable pyrolyzer combined with a gas chromatography/mass spectrometry (Py-GC/MS) analysis system. Evolved gas analysis (EGA/MS) indicates that the peak temperature for the decomposition of WFN in the absence of catalysts was around 420−480 °C whereas the temperature decreased down to 380−420 °C in the presence of CSS or commercial CaO catalysts. The yield of ε-caprolactam reached 66 wt.% in a catalytic depolymerization condition at 410 °C for 2 min with a 1:5 WFN/CSS weight ratio by using the Py-GC/MS system. Based on these experimental results, CSS should be an alternative catalyst for the recovery of the ε-caprolactam monomer from the WFN.