Five corn. surface-active agents used for fire extinguishing were studied for foaming power, surface tension and bio-degradability in aq. solns. The free adsorption energy, surface excess concn. and diffusion coeffs. were calcd. from the kinetic curves. The most stable foam was produced in air-liq. system contg. alkylpolyglucoside, while the highest biodegradability was offered by the sulfonated alpha-unsatd. fatty alcs.