Ideal microsensors would be cost effective, efficient, and stable, detect low concentrations of a certain gas in a working environment, and be able to operate in real time, i.e., monitor continuously. Among the compounds being investigated for development into microsensors are the phthalocyanines (Pcs), in particular in the form of thin films. The advantages and problems of Pc thin films are discussed, and the latest results for the detection of toluene and nitrogen oxides in air, including the response and recovery times, are presented.