Novel complexes of thorium(iv) and lanthanum(III) have been synthesized by their action with triphenylphosphinimino-AT group ligands, namely (i) (triphenylphosphoranylidene)acetohydrazide and (II) A:- (triphenylphosphoranylidene)nicotinohydrazide. The present work describes the studies on the coordination behaviour of all these complexes and they have been characterized by the FT-IR, 1H, 13C and 31P NMR spectroscopic techniques. Further these complexes were tested against antibacterial activities. © 2015 Scientific Publishers. All Rights Reserved.