Disclosed are rifamycin derivatives having antibacterial activities, wherein the compounds have the following general formula: wherein: R is hydrogen or acetyl; R1 and R2 are independently selected from the group consisting of hydrogen, (C1-4) alkyl, benzyloxy, mono- and di-(C1-3) alkylamino-(C1-4)alkyl, (C1-3)alkoxy, (C1-4) alkyl, hydroxy-methyl, hydroxy-(C2-4)-alkyl, and nitro or R1 and R2 taken together with two consecutive carbon atoms of the pyridine nucleus form a benzene ring optionally substituted by one or two methyl or ethyl groups and R3 is hydroxyalkyl (C1-4). In addition, processes to obtain these compounds are described.