[en] With the aim of determining masses of fission fragments by measuring velocities and kinetic energies, specially adapted time-of-flight detectors and ionization chambers were developed. The combination of both the time-of-flight and ionization chamber, to produce an energy-time-of-flight spectrometer, was tested with fragments from the /sup 235/U(n,f) reaction. In the light group of fission fragments, all masses are resolved individually with a mass resolving power m/δm = 170 for m = 95. At high energies also the heavy masses are resolvable. A possible nuclear-charge determination by the instrument is discussed