Ten new transition metal complexes (1–10) with 4-[2-(2-chlorobenzy-lidene)hydrazinyl]-7H-pyrrolo[2,3-d]pyrimidine (HPPHoCB) was prepared. 4-[2-(2-Chlorobenzylidene)hydrazinyl]-7H-pyrrolo[2,3-d]pyrimidine of general formula [C13H10ClN5], was prepared through the condensation reaction of 2-chlorobenzaldehyde with pyrrolopyrimidinehydrazide. The characterization of the new formed compounds was done by physico-chemical studies, conductance measurement, magnetic susceptibility data, 1H-NMR, UV-Visible, ESR, FT(IR) spectroscopy and elemental analysis. In addition, the structure of the complexes Cr(III), Fe(II), Co(II), Ni(II) and Cu(II) has been determined by X-ray diffraction method. The prepared HPPHoCB ligand act as bidentate ligand and coordinate with central metal ions through nitrogen of azomethine and pyrrolo groups. The low molar conductance values in nitrobenzene indicate that the metal complexes are non-electrolytes in nature. The magnetic moments and electronic spectral data suggest octahedral geometry for the Cr(III), Mn(II), Co(II), Ni(II), and Fe(II) complexes, tetrahedral geometry for Zn(II), Cd(II), Hg(II) complexes and square planar for Pd(II) and Cu(II) complexes. The HPPHoCB ligand and its metal complexes were screened for antimicrobial activities against two Gram-positive bacteria (Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121), two Gram-negative bacteria (Escherichia coli MTCC 1652 and Pseudomonas aeruginosa MTCC 741), and Fungus (Aspergillus niger, Aspergillus flavous and Fusarium species) as well as for cytotoxic studies against Artemia salina . The synthesised metal complexes were found more active against both bacterial as well as fungi in antimicrobial and cytotoxic screening test than that of HPPHoCB ligand.