Two Pd(II) complexes of 7-azaindole-3-carboxaldehyde (7AI3CAH) were synthesized. Structure of Pd2(7AI3CA)4 was confirmed by XRD, IR, Raman and DFT studies. In trans-PdCl2(7AI3CAH)2, palladium is bonded to two Cl and two pyridine N atoms. A detailed interpretation of the IR and Raman spectra is reported. trans-PdCl2(7AI3CAH)2 revealed remarkable cytotoxicity against T47D cancer cell lines. Display omitted New Pd(II) complex, trans-PdCl2(7AI3CAH)2, containing 7-azaindole-3-carboxaldehyde (7AI3CAH) and the dinuclear complex Pd2(7AI3CA)4·DMSO with the deprotonated ligand (7AI3CA) have been prepared and characterized by X-ray crystallography, infrared and Raman spectroscopy, DFT calculations and antiproliferative activity studies. A single crystal X-ray analysis of Pd2(7AI3CA)4·DMSO has shown that the complex crystallizes in Cmca space group with the following unit cell dimensions: a = 15.6593(9), b = 17.9444(8), c = 13.8915(7) Å, V = 3903.5(3) Å3, Z = 4. Two ligands and DMSO solvate molecule are disordered. In this complex, the Pd24+ unit is surrounded by four N-deprotonated 7AI3CA− anions with a Pd–Pd distance of 2.7122(12) Å. Vibrational spectroscopic studies have revealed that in trans-PdCl2(7AI3CAH)2 complex, palladium(II) is bound to two pyridine nitrogen atoms of 7AI3CAH and to two chloride ions, in a square-planar trans arrangement. Comprehensive DFT calculations (including geometry optimizations, theoretical vibrational spectra and HOMO/LUMO orbitals) were performed for the four possible isomers of the dinuclear complex Pd2(7AI3CA)4 and for two isomers of PdCl2(7AI3CAH)2 using the B3LYP method with the 6–311++G(d,p)/LanL2DZ basis sets. The results have shown that the most stable isomers are: cis-(2,2)-Pd2(7AI3CA)4 for the dinuclear complex and trans-PdCl2(7AI3CAH)2 for the mononuclear complex. Detailed vibrational assignments of the experimental infrared and Raman spectra of both the palladium(II) complexes have been made on the basis of the calculated potential energy distributions (PEDs). The antiproliferative activity of trans-PdCl2(7AI3CAH)2 has been tested against the following human cancer cell lines: T47D and MCF7 (breast cancer), A549 (lung carcinoma), A2780 (ovarian cancer) and one normal cell line BALB/3T3 (mouse fibroblast). The trans-PdCl2(7AI3CAH)2 has revealed a remarkable cytotoxicity against the T47D tumour cell line (IC50 = 4.77 ± 1.61 μM), which is over three-times higher than the clinically used cisplatin (IC50 = 16.3 ± 3.9 μM). A study on stability of trans-PdCl2(7AI3CAH)2 in DMSO solution has been performed by FT-IR (ATR) spectroscopy.