Multimode microthrusters are capable of both high specific impulse electrical operation and high thrust chemical operation, allowing a high degree of mission flexibility for small satellites. This technology requires a monopropellant capable of sustaining both modes of propulsion, through catalytic exothermic decomposition (chemical mode) and electrospray (electric mode). Previous research has identified a double-salt ionic liquid consisting of 41% wt. 1-ethyl-3-methylimidazolium ethyl sulfate and 59% wt. hydroxylammonium nitrate as a promising propellant candidate. The objective of this work is to measure its linear burn rate. The burn rate is measured through pressure-based and high-speed imaging methods in a fixed-volume pressurized reactor across a pressure range from 0.5 to 10 MPa. Its performance is compared to benchmarks 80% wt. hydroxylammonium nitrate-water and nitromethane propellants, both of which show good agreement with the literature. The burn rate of the multimode monopropellant is found to follow an exponential law eb = 5. 35e1.11P between 0.5 and 3 MPa and being approximately constant at 140 mm/s between 3 and 10 MPa.