The new lanthanide(III) complexes with quinoline derivative (MQAP) obtained by the reactio n between 3-formyl-2- mercapto quinoline with 4-amino pyridine have been synthesized and characterized by elemental analysis , molar conductance, magnetic moment measurements, FT-IR, e lectronic spectra, 1 HNMR spectra, FAB mass spectra, and thermal analysis studies. The molar conductance stu dies indicate non-electrolytic behavior of the comp lexes. The IR and 1HNMR studies indicate that MQAP acts as mono b asic bidentate ligand of potential donar site of az o methine nitrogen and thiolate sulphur. TG and DTA studies o f La(III) and Sm(III) complexes indicate the presen ce of two coordinated water molecules along with two nitrate and two MQAP moieties. Based on these studies the c omplexes have been formulated as [Ln(MQAP) 2 (H 2 O) 2 ](where Ln = La, Pr, Nd, Sm, Eu, Gd, Yb) with coord ination number 8. The cytotoxicity of the ligand and Ln(III) complexe s have been screened against cancer cells line HeLa (Cervical cancer cells, Human), which reveals that Ln(III) co mplexes shows moderate cytotoxicity against tested cell lines.