An ex perimental test apparatus and procedure for measur ing ero sive burning rates of so lid rocket pr opellant is described in the present paper. A g as gener ator in the test moto r produces a hig h velocity g as flow ing through a t ransit ion sect ion into a rectang ular channel w hich co ntains the test pr opellant sample. The sample is ig nited by cr oss-flow and burns along the normal dir ectio n of the burning sur face. The bur ning rate is direct ly measured by pho to graphing the ablat ing grain w ith CCD through a quart z w indow mo unted on the test sect ion. The elect rical signal t ranslated f rom image o f the f lame is sampled and pr oceeded by a computer, which makes it possible to determinen instantaneous burning rates o f the test propellant as a funct ion of t ime.