Synergism,beta in two separate surfactant mixtures of sodium dodecylsu
lphate(SDS)/sodium octanoate(NaC8) and tetradecyltrimethyl ammonium br
omide(TTAB)/cetyltrimethylammonium bromide (CTAB) system were calculat
ed and contrasted with the theoretical value at critical micelle conce
ntration, cmc. Results showed a negative value of -1.0 and -0.48 for t
he molecular interaction parameter, beta of both anionic and cationic
systems respectively. Its corresponding absolute value is lower than t
he absolute value due to the ratio of its logarithmic cmc.