Cyanide is a major cost centre in gold processing plants, and establishing the causes of cyanide loss can result in significant savings. The deportment of cyanide is complex, and can include volatilization, precipitation, complexation with metals, oxidation to cyanate or ammonia, and reaction with sulfide minerals to form thiocyanate. This paper presents a simple methodology using thermodynamic constants and solution analyses, to determine the speciation and deportment of cyanide in gold plant liquors and solids. Samples with different ore mineralogies and chemistries were assayed using the described methodology, and compared with results obtained by direct measurement using several techniques. The methodology that was developed enables cyanide deportment information to be obtained relatively easily. As expected, copper- complexes as both tricyano and tetracyano species were important in the samples studied. Importantly, meaningful analysis of cyanide in the presence of copper is obtained because the changing equilibrium levels of the copper cyanide complexes are taken into account in the analysis. Thiocyanate can account for a considerable amount of the cyanide that is consumed. The loss of cyanide die to volatilization can be significant in highly saline solutions, and this can also be estimated. Adsorption of cyanide and thiocyanate on to solids can also be important, depending on the mineralogy involved.