Cumulative yields of the short lived105Ru,107–109Ru isotopes in the spontaneous fission of252Cf have been determined by a fast radiochemical separation followed by gamma spectrometry. The cumulative yields of105Ru,107Ru,108Ru and109Ru are 7.20 ±0.30, 6.35±0.35, 5.89±0.29 and 4.08±0.30 respectively. The value of109Ru has been determined for the first time. From the cumulative yields the chain yields for mass chains 105, 107, 108 and 109 are obtained.