Toussidé is a symmetrical high stratovolcano, the second highest peak in Tibesti and the highest peak in the western Tibesti mountains. In the past it was considered to be lower, only , before a higher summit height was determined by Jean Tilho and W.G. Tweedale (1920). It rises above the surrounding landscape and covers a base of , dominating the surroundings. The summit cone is formed by lapilli, pyroclastics and scoria, one half has a white colour and the other half is black; some areas are white from fumarolic alteration. Lava flows emanate from Toussidé in a radial pattern and reach lengths of , covering an area of . These flows descended valleys towards the west and may have buried an older volcanic edifice of Toussidé. The flows have a ropy appearance with a diverse surface texture, including bubbly, glassy and porphyric textures, which are very fresh and free of erosion. The surface of the flows is rough and can be a problem to climbers. The relatively steep slopes of Toussidé may reflect the existence of a lava dome underneath the younger lavas; some flows may have originated from parasitic vents.