The polyhydroxylated silane network of a sol-gel protected immobilised Saccharomyces cerevisiae against the effects of five organic solvents. The viability of immobilised yeast directly correlated with the logarithm of the partition coefficient of the solvent in an octanol/water two phase system increasing the decimal reduction time (D) and reaching the maximum with octanol, the most hydrophobic solvent assayed. The D value increased from 0.16 min for free yeast to 1.9 and to 22 min for immobilised yeast exposed to ethanol and 1-octanol respectively.