The miniaturisation trend of today is not slowing down. Assemblies have to provide more power while the space available remains the same or becomes smaller. In order to meet the increasing requirements, so called non-conventional removal processes are being developed. One of these removal processes is laser chemical machining which is characterized by a gentle material removal and low energy input. The process window of laser chemical machining as well as the associated removal rates are limited due to the shielding effect of the gas bubbles as a result of laser-induced boiling process. In previous investigations, an influence of the viscosity of the electrolyte on the boiling process during laser chemical machining could be observed. In order to investigate the influence of viscosity on the laser chemical process in more detail, the viscosity of the electrolyte is increased by an additive (polyethylene glycol (PEG)) in the present work. The experimental investigations were carried out with phosphoric acid and the material titanium grade 1. The experimental investigations show that the upper limit of laser power within the process window decreases with increasing amounts of PEG in the electrolyte and thus with increasing electrolyte viscosity. Consequently, the maximum removal rates decrease. Furthermore, previously unknown removal profiles were observed at laser powers in the high power range of chemical laser machining. The observed profiles are characterised by half-rings in the processing direction. The reduction of the process window at increased electrolyte viscosities can be attributed to the laser-induced boiling process during laser chemical machining. Higher electrolyte viscosities increase the gas bubble diameter. In addition, the gas bubbles adhere longer to the workpiece surface. A comparison of the radii of the detected half-rings with the gas bubble diameters during laser chemical machining, shows that the radii of the half-rings are comparable to the gas bubble diameters. Therefore, it can be assumed that a correlation exists between the shielding gas bubbles and the resulting structures.