The voltammetric determination of trace amounts of gold has been studied using a chemically modified electrode. The role played by the host molecule attached to a glassy carbon electrode (GCE), i.e. 8,9,17,18-dibenzo-1,7-dioxa-10,13,16-triazacyclooctadecane (DDTC), was examined by electrochemical and spectrochemical techniques. Cathodic stripping voltammetry (CSV) was applied to study the various parameters affecting the affinity of gold ions by a DDTC modified electrode as well as the interference by other ions. Finally, the method has been successfully applied to determine gold traces in a geological sample. In addition, the formation of an AuCl4--DDTC complex was followed and its formation constant was determined by spectrophotometry.