The electrodeposition of palladium-gold alloy was investigated in an ambient temperature ionic liquid electrolyte, 1-ethyl-3-methylimidazolium chloride tetrafluoroborate system (EMI-Cl-BF4), containing palladium(II) and gold(I). Compact alloy deposits were obtained with galvanostatic electrolysis. The Pd content in the deposited Pd-Au alloy increases with increasing current density and the Pd mole fraction in the plating bath. For deposits obtained under mass-transport-limited current, the Pd content in the deposited alloys approximated the Pd mole fraction in the plating bath. The deposition temperature affected the homogeneity of the deposited Pd-Au solid solution. Data collected from X-ray powder diffraction experiments showed that Pd-Au alloys deposited at temperatures higher than 80 degreesC were homogeneous Pd-Au solid solutions. The scanning electron micrographs of the deposits revealed nodular particles. The particle size decreased with increasing deposition current. (C) 2004 The Electrochemical Society.