The invention relates to a process carried out continuously in one or more reactors connected in series for the preparation of sodium titanate nanotubes and their derivatives obtained by ion exchange and/or thermal treatment, by reacting titanium oxides with sodium hydroxide under suitable hydrothermal conditions to obtain or control the morphology of nanostructural titanates. The reaction mixture is introduced continuously into the reactor at a feed rate that is the same as the rate of discharge of the product. When more than one reactor is used, the material leaving the first reactor is used to feed the next reactor, and a differential of temperature is applied between the reactors in such a way as to obtain in the average, a temperature of between 60° C. and 180° C.