Using rocket-grade hydrogen peroxide and a nontoxic, hypergolic miscible fuel, a 150-lbf thrust class pintle injector engine has been developed and tested with the aim of characterizing injector performance under a variety of design and operating conditions. Rapid, reproducible ignition was sustained under a wide range of operating conditions using the new hypergolic propellant combination. Parametric studies were undertaken to assess the influence of characteristic chamber length L*, chamber diameter-to-pintle diameter ratio, total momentum ratio, secondary-to-primary hole diameter ratio, and the pintle length-to-pintle diameter ratio. High performance has been achieved in both steady-state and pulse mode operation.