The design and application of an electrochemical micro-flow reactor for the aldol reaction of acetone to diacetone alcohol (DAA) is reported. The modular reactor could be readily disassembled and reassembled to change the electrodes, incorporate a membrane and remove possible obstructions. The productivity and efficiency was quantified. Using a platinum deposit as electrocatalyst or an inert glassy carbon electrode as working electrode, the maximum obtainable equilibrium concentration of +/- 15 m% was reached after a single pass up to a flow rate of 8 ml min(-1), yielding 0.57 g min(-1) DAA (3.46 mmol cm(-3) min(-1)) at an efficiency of 0.33 g C-1 on platinum and 0.50 g min(-1) (3.04 mmol cm(-3) min(-1)) at 1.20 g C-1 on glassy carbon. Note that no optimisation studies have been made in the present paper. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.