AbstractA number of new diesterquats and anidoester quats were synthesized and tested for biodegradation and softening. Methyldiethanolamine, 3‐methoxylpropylamine, diethanolaminopropylamine, aminoethylethanolamine, dimethylethanolamine, and diethanolamine were reacted, either “as is” or after alkoxylation, with tallow fatty acid and further converted into dialkyl quats. The diesterquat from diethanolisopropanolamine was by far the best of the ester quats synthesized in overall biodegradation, softening, and cost/ease of manufacture. It appears that two ester groups are needed for ready biodegradation as opposed to an amide‐ester combination. Increasing unsaturation of the alkyl chains within a molecule increases its rate of biodegradation slightly.