Positive effects of green exercise on physical and psychological wellbeing have been found, yet little is known about the underlying cognitive mechanisms responsible for such effects. The purpose of this visual sensation study was to establish the extent to which the color green, as a primitive visual feature of many natural environments, contributes to the green exercise effect. Fourteen participants performed three moderate-intensity 5-min cycling tasks (50% peak power output) while watching video footage of a rural cycling course that simulated cycling through a real natural environment. The three randomly counter-balanced video conditions were unedited (V GREEN ), achromatic (V GRAY ) or red filter (V RED ). Lower total mood disturbance and ratings of perceived exertion were found during the V GREEN compared to V GRAY and V RED . Feelings of anger were higher after V RED compared to the other conditions. Feelings of tension, depression, fatigue, vigor, and confusion did not differ among conditions. This is the first study to show that the color green, as a primitive feature of visual sensation, has a contributory effect toward positive green exercise outcomes. © 2012 American Chemical Society.