Organometallic-cyclodextrin inclusion compounds were obtained by the treatment of molybdenocene dichloride (Cp 2 MoCl 2 ) with the modified cyclodextrins (CDs) heptakis-2,3,6-tri-O-methyl-b-CD (TRIMEB) and 2-hydroxypropyl-b-CD (HPbCD) in aqueous solution. The products were isolated by liophilisation and characterised in the solid-state by powder XRD, thermogravimetric analysis, Raman and FTIR spectroscopy, and 13 C CP MAS NMR spectroscopy. The results are consistent with inclusion of Cp 2 MoCl 2 , rather than hydrolysis products such as [Cp 2 Mo(H 2 O)X] + (X = Cl, OH) or [Cp 2 Mo(H 2 O) 2 ] 2+ . The pure non-included metallocene Cp 2 MoCl 2 and its inclusion compounds with unmodified b-CD, TRIMEB and HPbCD were screened for their potential antiproliferative and cytotoxic activity, in both human cancer and healthy cell lines. Inclusion in CD was found to enhance the cytotoxic effect of Cp 2 MoCl 2 , with the TRIMEB adduct displaying the highest anti-tumour activity, along with the lowest toxicity towards non-neoplastic cells.