The paper describes the optimization of the wavelength pair to be used in differential absorption lidar measurements of tropospheric ozone. Along with the usual requirements for optimum lidar performance, aerosol and aerosol gradient effects and sulfur dioxide cross sensitivity have been given special attention. For the measurement and reference, laser-beam wavelengths of 280.91 and 282.72 nm are proposed. Ozone lidar verification measurements with a UV photometric analyzer show excellent agreement and confirm the theoretical finding that ozone concentration uncertainties due to aerosol effects are insignificant under visibility conditions like those prevailing on a warm summer day directly above a deciduous-coniferous mixed forest canopy. The lidar used is described in some detail, and a few examples of measured gas distributions are presented.