A new method to synthesize $\alpha$-oximino-$\alpha$-haloketones using alkyl thionitrites was developed under mild conditions. The reactions of $\alpha$-haloketones with t-butyl thionitrite or n-butyl thionitrite in anhydrous ether containing gaseous hydrogen chloride under mild conditions ($25-35^\circ C$) afforded the corresponding oximes. In the case of using more stable t-butyl thionitrite, the better yields of oximes were obtained than using n-butyl thionitrite probably due to the instability of n-butyl thionitrite. Since the sulfurnitrogen bond of thionitrites is relatively weaker than the oxygen-nitrogen bond of nitrites and also $RS^-$ is better leaving group than $RO^-$ in the nitrosation step, thionitrites are considered to be better reagents than nitrites for the nitrosation of $\alpha$-haloketones. Undoubtedly, this reaction appears to be initiated by nitrosation on the carbon attached to halogen of $\alpha$-haloketones. Alkyl or benzyl chloromethyl ketones reacted with t-butyl thionitrite to give the corresponding oximes in good yields (80-95\%). While, in the case of aryl halomethyl ketones, the yields of oximes were low (10-40\%).