The present invention relates to novel crystalline, water-soluble salts of a plk inhibitor. Such crystal salts are for example L-tartrate, succinate, phosphate, mesylate, maleate, L-malate, hydrochloride, fumarate (half mole of counterion), fumarate, citrate (half mole of counterion), benzenesulfonate and L-aspartate (half mole of counterion). New crystal forms of the base as well as solvates and hydrates of such new salt forms, a process for their preparation, their utility in therapy and to the pharmaceutical compositions containing them are also claimed and described in the present application.La présente invention concerne des sels cristallins hydrosolubles inédits dun inhibiteur de la PLK. Lesdits sels cristallins sont, par exemple, du L-tartrate, du succinate, du phosphate, du mésylate, du maléate, du L-malate, de lhydrochlorure, du fumarate (une demi mole dun contre-ion), du fumarate, du citrate (une demi mole dun contre-ion), du benzènesulfonate et du L-aspartate (une demi mole dun contre-ion). Linvention concerne également des formes cristallines inédites de la base, ainsi que des solvates et des hydrates de ces formes de sels inédites, leur procédé de préparation, leur intérêt thérapeutique et des compositions pharmaceutiques en contenant.