Rates of mass and heat transfer at vibrating helical coils were studied by the electrochemical technique with the object of using helical coils as heat exchanger/reactor for conducting liquid-solid diffusion controlled reactions. Variables studied were frequency and amplitude of vibration, tube diameter, and superimposed axial flow velocity. The data for vibrating coil (batch reactor) were correlated for The data were found to be consistent with the analogy model. For vibrated helical coils with superimposed axial flow, the data were correlated by the equation: Importance of the present results in the design and operation of heterogeneous reactors used to conduct diffusion controlled exothermic reactions involving heat sensitive materials was pointed out. Also the importance of the present results in the design and operation of shell and helical tube heat exchangers of improved performance was highlighted. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 3141-3149, 2017