A new chiral organometallic nucleoside analogue containing ruthenocene is reported, in which alkylthymine and alkylhydroxyl groups are attached in adjacent positions on one cyclopentadienyl ring. The synthetic procedures for this metallocene derivative and two control compounds are described, along with their characterisation by cyclic voltammetry and X-ray crystallography. Their biological activities in a human pancreatic cancer cell line (MIA-Pa-Ca-2) were significantly lower than those of three previously reported analogous ferrocene compounds, indicating that the choice of metallocene metal atom (Fe or Ru) plays a pivotal role in determining the anticancer properties of these nucleoside analogues, which in turn suggests a different mode of action from that of a conventional nucleoside analogue.