Disclosed herein is a process for preparing a 5-(2-{ [6-(2,2-difluoro-2-phenylethoxy)hexyl]amino} -1-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one compound of formula (I), comprising: reacting, in a xylene solvent, a compound of formula (V), wherein P1 and P2 represent hydroxy protecting groups and L is a leaving group, with 6-(2,2-difluoro-2-phenylethoxy)hexan-1-amine of formula (IV), to give a compound of formula (III), which is deprotected to give a compound of formula (I). In one embodiment P1 is a benzyl group and the P1 deprotection step is effected by hydrogenation (such as in the presence of palladium on charcoal optionally in acetic acid, or a mixture of acetic acid with an alcohol or with an ester), and/or (b) P2 is a tert-butyldimethylsilyl group and the P2 deprotection step is effected by reaction with tetra n- butyl ammonium fluoride trihydrate or with hydrogen chloride. In one embodiment the compound of formula I is a hemiapadisylate or mesylate salt.
