Based on the recently reported asymmetric hydrogenation of methyl acetoacetate in a continuous-flow, gas phase reaction using Supported Ionic Liquid Phase (SILP) catalysis, this study deals with the even more challenging asymmetric reduction of the alpha-keto ester methyl pyruvate. Different support materials, ligands and ionic liquids were screened to identify an optimized Ru-based SILP catalyst. With Ru-BINAP dissolved in the ionic liquids 3-hydroxypropylpyridinium bis(trifluoromethylsulfonyl)imide on silica 100, stable catalyst performance could be obtained for more than 50 h time-on-stream. At 95 degrees C and with a residence time in the reactor of less than 3 s a stable product yield of 80-84% was obtained with moderate but stable enantiomeric excess of 26-30%. (C) 2013 Elsevier B.V. All rights reserved.