The invention provides a crystalline naphthalene-1,5-disulfonic acid salt of biphenyl-2-ylcarbamic acid 1-{9-[(R)-2-hydroxy-2-(8-hydroxy-2-oxo-1,2-dihydro-quinolin-5 -yl)ethylamino]nonyl}piperidin-4-yl ester or a solvate thereof. This invention also provides pharmaceutical compositions comprising such a salt or prepared using such a salt; processes and intermediates for preparing such a salt; and methods of using such a salt to treat a pulmonary disorder.