The merging of liquid jets approaching at high momentum results in a rapidly deforming impingement zone that promotes close contact and mixing between the two fluids. This close contact enhances the rate of the chemical reaction and is of interest for use in the delivery of non-Newtonian liquids such as gelled propellants in rocket injection systems. In the current work, synchrotron-based X-ray radiography and fluorescence are performed to determine the liquid mass distributions for 0.508-mm-diameter non-Newtonian impinging jets of shear-thinning fluids (viscosities similar to 100-1000 Pa.s) compared with that of Newtonian fluids (viscosities similar to 0.001-0.1 Pa.s). The X-ray measurements quantified the ability of shear-thinning fluids to mimic the in situ jet compression, lateral expansion, initial sheet formation, and binary mixing behavior of viscous Newtonian fluids for jet velocities as low as 9.1 m/s. However, the shear-thinning fluids seemed to reach a limiting regime by 18.3 m/s and could not achieve jet breakup and atomization even up to 36.6 m/s. Further downstream, the shear rate drops and the viscosity of the gelled fluid recovers, leading to a mass distribution that depends on the gellant concentration and initial jet velocity. These data help to determine the parameters that affect the degree of mixing and liquid sheet formation at various stages of jet interaction for the injection of non-Newtonian liquids.