Abstract: A full bore spectral gas holdup tool that measures gas holdup that is corrected for effects of the flowstream lamination and the salinity of the liquid in the flowstream. The basic methodology utilizes spectral data from two gamma ray detectors at different spacings from a nuclear source that emits gamma radiation. 57Co is the preferred source and the gamma ray detectors are scintillation spectrometers. In addition to a full bore gas holdup measurement, the spectral gas holdup tool also provides indications of the degree of flowstream lamination and the salinity of the liquid in the flowstream. An iterative data processing method optimizes the accuracy of the measured flowstream parameters.