•Aniline electropolymerisation shown to not be solely controlled by pH in DESs.•Dynamic light scattering shows that the monomer is in a colloidal phase for all systems where electropolymerisation occurs.•Size of PANI particles similar to dimensions of colloidal dispersed phase.•Aniline emulsions tend to form when water is added to DESs. The electropolymerisation of aniline is a well-studied and often used technology. While the mechanism has been investigated in a variety of media these have all concentrated on understanding the process on a molecular level. Anomalies in the electropolymerisation of aniline in four deep eutectic solvents, DESs, using urea, ethylene glycol, glycerol and oxalic acids as hydrogen bond donors with choline chloride led to an investigation of the aniline phase behaviour. It was only with oxalic acid that polymerisation was achieved and adjusting the pH of the other DESs using sulphuric acid did not enable polymer formation suggesting that pH was not the only factor enabling polymer growth. When 10 wt% water was added, polymers could be grown in all the DESs despite negligible change in solution pH. Dynamic light scattering showed that polymer only formed in systems where aniline formed an emulsion. Scanning electron microscopy, SEM and atomic force microscopy, AFM showed that the polyaniline films were formed of an agglomeration of small particles of the same dimensions as the dispersed monomer phase in solution. This suggests that the droplets of the monomer arrive at the electrode surface where they polymerise. This provides the first evidence that polyaniline grows by an emulsion polymerisation mechanism even in aqueous solutions. Display omitted