The present invention relates to citrate salts of baricitinib, in particular to baricitinib mono- and dicitrate, as well as to crystalline and amorphous forms thereof, and to methods for their preparation. Furthermore, the invention relates to a pharmaceutical composition comprising an effective and/or predetermined amount of one or more citrate salts of baricitinib and to the use of said pharmaceutical composition as a medicament, in particular for the treatment of rheumatoid arthritis.