Spin-coated layers of ZnTPP have been used as optochemically interacting materials to detect 4-aminophenol, following the UV–vis optical absorption variations obtained by the exposure of the sensing layers to vapour analyte diluted in dry-air controlled atmosphere. A multichannel monitoring of the variation in the sensing layer main optical absorption bands after interaction with 4-aminophenol allow us to study the interaction mechanism between analyte and metalloporphyrin. Morphological characterization of the sensing layer was also performed by atomic force microscopy.