This study investigates colour harmony in visual ;experiments in order to develop a new quantitative colour harmony model. 017 the basis of new experimental results, colour harmony formulae were developed to predict colour harmony from the CIECAM02 hue, chroma, and lightness correlates of the members of two- or three-colour combinations. In the experiments. observers were presented two- and three-colour combinations displayed on a well-characterized CRT monitor in a dark room. Colour harmony was estimated visually on an 11 category scale from -5 (meaning completely disharmonious) to +5 (meaning completely harmonious), including 0 as the neutral colour harmony impression. From these results, mathematical models of colour harmony were developed. The visual results were also compared with classical colour harmony theories. Two supplementary experiments were also carried out: one of them tested the main principles of colour harmony with real Munsell colour chips, and another one compared the visual rating of the new models With existing colour harmony theories. (C) 2009 Wiley Periodicals, Inc. Col Res Appl, 35, 34-49, 2010; Published online 17 November 2009 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20558