A catalytic layer of CsNaX zeolite film was deposited on quartz capillary tube by flow synthesis method under hydrothermal conditions. The procedure involved seeding of the capillary tube with zeolite nanocrystals followed by controlled zeolite regrowth and crystallization under flow conditions. The CsNaX capillary microreactor was employed in Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate. The sensitivity of the catalyst to water produced by the condensation reaction was remedied with the use of solvents. Ninety nine percent benzaldehyde conversions were obtained using a traditional solvent DMSO, but decreased with time as water accumulates and poisons the catalyst. Replacing the solvent with an ionic liquid (IL-BMIC) improves water absorption and the catalyst displayed better (i.e., > 99%) and stable conversions. (c) 2012 Elsevier B.V. All rights reserved.