The respiration of Candida lipolytica on n-tetradecane is decreased in the presence of bentonite. This inhibition is less pronounced by the introduction of hydrophobic chains on the bentonite. Oxygen demand of resting cells varies with the length of hydrophobic chains. In fermentor, addition of adsorbant does not stimulate growth, but assimilation of n-tetradecane is enhanced with certain concentrations of the adsorbant. On glucose, addition of hydrophobic chains on the adsorbant does not change the effects of bentonite on exogenous respiration and substrate assimilation.