Metal oxides and metal oxide​/carbon composites are entering the development of new technologies and should therefore to be prepd. by sustainable chem. processes. Therefore, a new aspect of the reactivity of cellulose is presented through its solid​/gas reaction with vapor of titanium(IV) chloride in anhyd. conditions at low temp. (80 °C)​. This reaction leads to two transformations both for cellulose and titanium(IV) chloride. A reductive dehydration of cellulose is seen at the lowest temp. ever reported and results in the formation of a carbonaceous fibrous solid as the only carbon-​contg. product. Simultaneously, the in situ generation of water leads to the formation of titanium dioxide with an unexpected nanoplate morphol. (ca. 50 nm thickness) and a high photocatalytic activity. We present the evidence showing the evolution of the cellulose and the TiO2 nanostructure formation, along with its photocatalytic activity. This low-​temp. process avoids any other reagents and is among the greenest processes for the prepn. of anatase and also for TiO2/carbon composites. The anisotropic morphol. of TiO2 questions the role of the cellulose on the growing process of these nanoparticles.