There are described a new class of organic dyes containing silane groups, the composite pigments obtainable therefrom by associating them with a substrate (SiO.sub.2, TiO.sub.2, Al.sub.2 O.sub.3), and the processes for preparing same.The silane organic dyes have the formula (I): ##STR1## wherein all substituents are defined later. The silane dyes (I) are utilized per se for dyeing natural fibres, such as wool, and man-made fibres, such as the polyamide, polyester, polyacrylic fibres and the like, while the composite pigments prepared from said dyes by association with an inorganic substrate are employed in paints, air enamels and stoving enamels, in the pigmentation of plastics, in the inks, in the printing of textiles etc.