Ferredoxins are iron-sulfur proteins that transfer electrons in different cellular processes. In Bacillus cereus there are two genes for ferredoxins that have been identified, one present with a [2Fe-2S] cluster (BC2795) and one with a [4Fe- 4S] cluster (BC1483). These proteins can potentially receive electrons from three possible ferredoxin-NADP+-reductases, and further activate different enzymes. In this project, the starting point was to purify and structurally characterize the two ferredoxins in B. cereus and potentially their interactions with redox partners. For the [4Fe-4S] ferredoxin several attempts to overexpress this protein was unsuccessful. However, the [2Fe-2S] ferredoxin (106 amino acids, 11.4 kDa) was successfully overexpressed in Escherichia coli. This [2Fe-2S] ferredoxin was purified in a series of purification steps involving ammonium sulphate, desalting column, Q Sepharose or DEAE columns, and Superdex 75 column. The purification procedure showed to be troublesome because of possible low iron-sulfur cluster content, and because of low UV-vis detection due to the absence of tryptophanes and tyrosines in the protein. Due to the high content of apoprotein, it was also tried to establish a reconstitution procedure for BC2795. The apoform of the protein was crystallized. Nevertheless, it was not possible to solve the structure.