A porphyrin metal-organic framework CoTCPP with large surface area and the macrocyclic conjugated structures was constructed from [5,10,15,20- (4-carboxyphenyl)porphyrin] Co(III) and characterized. Furthermore, an electrochemical platform based on CoTCPP and ionic liquid (IL) immobilizing cytochrome c (Cyt c) was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometric current-time curve. The results of electrochemical and spectroscopic measurements showed that Cyt c remained bioactivity and achieved fast electron transfer on the IL/CoTCPP composite film modified electrode. The proposed modified electrode displayed linear response to NO2- in the range of 3.5-2800 mu M, with a lower detection limit (1.1 mu M) and smaller apparent Michaelis-Menten constant K-M (0.28 mM). Thus, the IL/CoTCPP composite film could be applied as a biocompatible platform for the direct electrochemistry and electrocatalysis for NO2- of Cyt c. (C) 2017 The Electrochemical Society. All rights reserved.