A coated acoustic wave sensor has been developed to selectively detect atmospheric ozone. The selective detection has been assessed using a variety of coatings: beeswax, gallic acid, indigo carmine, polybutadiene, potassium iodide and sodium nitrite.Polybutadiene was the most sensitive with a limit of detection of 55 ppb. The sensitivity was improved by operating at higher harmonics and was shown to increase linearly with harmonic up to the 11* harmonic. This novel work shows that ozone detection can be improved by operating at the crystals' harmonic frequencies and in conjunction with a suitable flow rate, a potentially highly sensitive and fast response sensor can be created based on acoustic wave technology.