We have developed a new soft x-ray spectrometer covering the photon energy range 50–500 eV. It employs a free-standing transmission grating coupled to a microchannelplate detector. The performance of the device was tested by using radiation from a synchrotron with a continuous spectrum. The detector shows a rather flat response over most of the useful spectral range, with an abrupt decrease in the sensitivity at the short-wavelength end. Its simplicity of operation makes the device attractive for such applications as the study of soft x-ray emission from laser-produced plasmas.