A mixed culture of methanol oxidizing bacteria has been cultivated on simple inorganic salts medium supplemented with methanol. Optimal growth occurred at 31°C, pH 6.0–6.3, and a methanol concentration between 1 and 2 ml/1, of medium. The maximum yield was 4.5 g dw/I and the mean generation time 3.2 hr. It was estimated that 41% of methanol carbon was converted into cell‐carbon, and that 73% of the inorganic nitrogen was converted to organic nitrogen. Copyright © 1969 John Wiley & Sons, Inc.