We first report the GaAs/ZnSe and InxGa1-xAs/ZnSe core/shell structured colloidal quantum dots (CQDs). GaAs based CQD, which are hard to obtain by the chemical synthetic method, can be prepared successfully using the acetylacetonate complex of indium and gallium as cationic precursors. We control the indium contents, and the photoluminescence emission is tuned from orange to deep red. In0.2Ga0.8As/ZnSe core/shell QDs show the best quantum yield of 25.6%. A ZnSe outer shell protects the core and improves quantum yield, and it shows a large red shift owing to the quasi-type-I band structure.