Formaldehyde detection in air is of particular interest since this compound is classified as carcinogenic by the International Agency for Research on Cancer (IARC). It is abundant indoors (with an indoor/outdoor ratio around 5 to 15) and has as main origin the emissions from building or furniture materials. Among all the strategies currently used to control formaldehyde concentrations, none of them combines both good selectivity, low detection limit and easiness of use at low cost. To achieve this goal, we focused on the specific reaction between fluoral-p and formaldehyde to develop a sensor made of an intrinsically conducting polymer and fluoral-p. Formaldehyde reacts with fluoral-p to produce 3, 5-diacetyl-1, 4-dihydro-2, 6-lutidine (DDL) and ammonia. Polyaniline (PAni) was chosen as the conducting polymer due to its ammonia sensitivity as previously described by the authors. The performances of this new formaldehyde sensor have been evaluated in terms of sensibility, response time and detection limit. © 2011 IEEE.