The purpose of this research is to investigate the color appearance and color connotation of unrelated colors. To investigate color appearance (i.e., brightness, colorfulness, and hue) for unrelated colors, 22 observers have answered their color appearance for 50 unrelated color stimuli using the magnitude estimation method. Perceptual data obtained by the experiment is compared with the color attributes data estimated by unrelated-color appearance models, CAM97u and CAM02u. It is found that both models perform reasonably well but the performance of CAM02u is better than that of CAM97u. For investigating color connotation for unrelated colors, 32 observers have judged their color connotation for the 50 unrelated color stimuli using the 10 color connotation scales (i.e., Warm - Cool, Heavy - Light, Modern - Classical, Clean - Dirty, Active - Passive, Hard - Soft, Tense - Relaxed, Fresh - Stale, Masculine - feminine, and like - Dislike), and semantic differential method is used for measurement. It is found that the color connotation models developed for related colors perform poorly for unrelated colors. Experimental results indicate that brightness attribute is confusing to estimate and does not affect color connotation significantly for unrelated colors. Based on the psychophysical data, new models for Warm-Cool, Heavy-Light, Active-Passive and Hard-Soft were proposed using CAM02u hue, brightness, and colorfulness. Color connotations for unrelated colors are classified into three categories, which Color solidity, Color heat, and Color purity. (c) 2013 Wiley Periodicals, Inc. Col Res Appl, 40, 40-49, 2015