Dematerialisation refers to the decline, over time, of material usage in industrial products. The subject of this paper is to identify the relationship between the material and knowledge content of several products. The issue is whether the knowledge content, through time, will be affecting the products, in terms of dematerialisation. Specifically, a study has been conducted on widely used products in order to determine the way they have changed through their life-timeline. Two different indicators have been introduced for the quantification of the trend, in terms of material and knowledge content.