This invention relates to a salt of 3-[6-(2-methoxyethyl)-3-pyridinyl]-2-methyl-8-(4- morpholinyl)-imidazo[1,2-b]pyridazine, a phosphodiesterase 10 enzyme (PDE10) inhibitor, as well as to pharmaceutical compositions comprising the same, the salt for use in the treatment or prevention of a central nervous system disorder, or a metabolic disorderand methods of treatment using the same.