Disclosed is a tosylate salt of an aminoalkyl tetracycline compound (4S,4AS,5AR,12AS)-4-7-Bis(dimethylamino)-9 { [(2,2-dimethylpropyl)amino]methyl} -3,10,12,12A-tetrahydroxy-1,11-dioxo-1,4,4A,5,5A,6,11,12A-octahydrotetracene-2-carboxamide (9-(2,2-dimethyl-propyl-aminomethyl)-minocycline) and a crystalline form of said tosylate salt. A polymorph of the crystalline form of this compound having an X-ray powder diffraction pattern with preaks at approximately 8.06, 13.02 and 18.83 2 degrees theta, is also disclosed. Also disclosed is a method for preparing the above mentioned crystalline tosylate salt.
