This invention relates to salts and crystal forms of (S)-6-chloro-7-(1,1-dimethylethyl)-2-trifluoromethyl-2H-1-benzopyran-3-carboxylic acid, Compound A, which is cyclooxygenase-2 inhibitor. The present invention provides a salt of compound A, a crystal form thereof, a process for preparing the said salt and a pharmaceutical composition thereof and its use. The salts and/or co-crystals of Compound A of the present invention show good formulation properties such as high aqueous solubility, good intrinsic dissolution, good crystallinity, good thermal stability or low hygroscopicity.