This paper presents part of the research project Greyness and spatial experience. Its main objective is to discuss the concept of neutral grey and to investigate the preconditions for perceiving neutral grey colours in different situations. Neutral grey is defined as having similarity only to black and white, not to the chromatic elementary colours.

Greyish colour samples have been observed with different backgrounds and in different light. One of these series is presented in detail in the paper, the conclusions from others are considered in the discussion, together with relevant literature. Greyish colours are seldom perceived as neutral, but rather tend to get a perceived hue, which depends on the observation situation. Inherent neutral grey colours are not found in nature. In production of materials and artefacts no tolerance level can assure a total lack of hue.

In conclusion we suggest that neutral grey should be considered as an abstraction, its unique but in practice unobtainable quality lying in its absolute lack of hue and chromaticness.