A process for preparing fexofenadine is described, which provides for the hydrolysis of 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidyl]-1-oxobutyl]-α,α-dimethylbenzeneacetic acid-alkyl ester, in a mixture of water and optionally an organic solvent, in the presence of a base; the carboxylate salt of 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidyl]-1-oxobutyl]-α,α-dimethylbenzeneacetic acid is thus obtained, which is then directly reduced as carboxylate in a basic environment with hydrogen in the presence of a suitable hydrogenation catalyst to give the carboxylate of fexofenadine, which is precipitated by neutralization of the solution.