A novel surfactant, dodecylammonium picrate (DDAP), was synthesized and its crystal structure was determined by X-ray diffraction analysis. DDAP's physicochemical properties were examined by spectral (infrared and nuclear magnetic resonance), thermal, microscopic, and conductometric studies. The results revealed the influence of counterion specificity on thermal solid-state transitions and solution properties: the Krafft point, the aqueous solubility, the critical micelle concentration, the degree of counterion binding, and thermodynamic parameters of micellization. Copyright 2000 Academic Press.