For the synthesis of colloidal ternary ZnCdSe nanorods, CdSe nanorods were first prepared under a mixture of tetradecylphosphonic acid/trioctylphosphine oxide surfactants at 250 degrees C, and then ZnSe shell layer was grown onto CdSe nanorods at 180 degrees C, forming CdSeZnSe core/shell nanorods. Green-yellow emitting ternary ZnCdSe nanorods were obtained by a subsequent alloying process at 270 degrees C for 1-3 h through the diffusion of Zn ions into CdSe nanorods. The photoluminescence quantum yield (QY) of ZnCdSe nanorods was 5%-10%, which is higher than that from pristine CdSe nanorods (0.6%). The QY of these alloy nanorods depends on the alloying time and is discussed in terms of compositional disorders and defects produced by the alloying process. The Raman and time resolved photoluminescence spectroscopies were used to understand the detailed alloying process from CdSeZnSe core/shell to ZnCdSe alloy nanorods.