Hydroxamic acid (HA) derivates displayed antibacterial and antifungal activities. HA with various numbers of carbon atoms (C2, C6, C8, C10, C12 and C17), complexed to different metal ions Fe(II/III), Ni(II), Cu(II) and Zn(II) were evaluated for their antimycobacterial activities and their anti-biofilm activities. Some derivates, among others HA12Fe2, inhibited the development of Mycobacterium tuberculosis, Mycobacterium bovis BCG and Mycobacterium marinum biofilms and could even attack pre-formed Pseudomonas aeruginosa biofilm. Proteomic profiles showed that the potential targets of HA10FeCl were mainly related to mycobacteria stress adaptation, involving cell wall lipid biosynthesis, drug resistance and tolerance, siderophore metabolism. This study provides new insights regarding the antimycobacterial activities of the HA and their complexes, especially about their potential antibiofilm activities.