In a work published in this journal by J.P.S. Cabral and A.R.W. Smith [J. Colloid Interface Sci. 149 (1992) 27], it is reported that the 1-dodecylguanidinium acetate (dodine) exhibits first CMC at 20-30 mu M and second CMC at 110-120 mu M in aqueous solution at 22.5 degrees C. Such low CMCs are unusual for ionic surfactants with dodecyl chain, and is quite interesting if this is the case. Thus, we investigated the micelle formation of dodine by electrical conductivity measurements. The specific conductivity, kappa, vs concentration plot showed no evidence for micelle formation up to a few hundreds mu M at 25 degrees C. The Krafft temperature of dodine was found to be approx. 52 degrees C. When conductivity measurements were made at 54 degrees C, a clear break point was observed in the kappa vs concentration plot at 9.5 mM, which must correspond to the CMC of dodine. This CMC value is quite normal for cationic surfactant with dodecyl chain. (C) 2007 Elsevier Inc. All rights reserved.