An improved process for the preparation of solifenacin succinate (1) involving resolution through diastereomeric crystallization is described. (1S)-IQL derivative (5) is esterified to form (1S)-ethoxycarbonyl IQL derivative (6) which is condensed with (RS)-3-quinuclidinol (7) to form a solifenacin diastereomeric mixture (8); this is subjected to resolution through diastereomeric crystallization to produce solifenacin succinate (1), which is used for the treatment of an overactive bladder.