Impulse generation experiments of a liquid propellant laser thruster were conducted using glycerin propellants in the energy range of 60 mJ ∼ 60 J. Momentum coupling coefficients and specific impulses were obtained from momentum impulse and propellant mass measurements. The maximum specific impulse was 18 s at the laser beam energy of 55 J. Experimental data were scaled in terms of the laser beam energy and the diameter of the glycerin droplet to extrapolate laser thruster performance. The results indicate that the diameter of the glycerin droplet must be less than 0.24 mm in these experiments to achieve specific impulse more than 1,000 s that will be required to compete with other space propulsion systems. © 2004 American Institute of Physics