A new, simple and selective spot test reaction For aromatic aldehyde detection is described. The sample is treated with 2-picoline methiodide in the presence of piperidine as catalyst. The maximum sensitivity is obtained by evaporating the reactants to near dryness in a boiling water-bath. The colored products varied between orange and pink. Aldehyde samples as small as 1.0. ug can be detected successfully. Interference of other carbonyl containing compounds is tolerated.