This paper presents a novel, in-line Electrical Resistance Rheometry (ERR) technique which is able to obtain the rheological information of process fluids, in-situ, based on electrical resistance sensing. By cross-correlating fluctuations of computed conductivity pixels across and along a pipe, using non-invasive microelectrical tomography sensors, rheometric data is obtained through the direct measurement of the radial velocity profile. A range of simple, Newtonian and non-Newtonian fluids, have been examined with the obtained velocity profiles independently validated using Particle Image Velocimetry (PIV); results from both ERR and PIV techniques are in excellent agreement. Comparison of the rheological parameters obtained from ERR with off-line rheology measurements demonstrated that ERR was able to perform with an accuracy of 98% for both Newtonian and non-Newtonian fluids. The ERR technique presented offers new capabilities of true in-situ analysis of fluids relevant to formulated products and in-pipe spatial and temporal analyses afford the simultaneous interrogation of localised and global mixing behaviour. (C) 2018 The Authors. Published by Elsevier Ltd.