The goal of this work was to deposit thin films of bismuth cobalt oxide, which is a rather unexplored yet promising multiferroic material, by Atomic Layer Deposition(ALD). However, in order to achieve this goal, first a suitable precursor combination for deposition of bismuth oxide by ALD had to be found. This work presents the first reported thin film deposition of ?-Bi2O3 by ALD. In addition, thin films of Co3O4 and CoO are for the first time reported deposited by ALD from the respective novel precursor combinations Co(thd)3/O3 and Co(thd)2/H2O (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate). Finally, BiPh3 (Ph = phenyl), Bi(t-OBu)3 (t-OBu = tert-butoxide) and Bi(thd)3 were all investigated for potential use as bismuth precursors in the ALD process. Thin films of Co3O4 deposited from the novel precursor combination Co(thd)3/O3 was investigated and a comparison to the already well investigated precursor combination Co(thd)2/O3 is given. Deposition and investigation of thin films in the Bi-Co-O system are also presented. However, an etching process was observed between the Bi(thd)3 precursors and the Co3O4 surface. A possible mechanism is presented.