The variations of plasma parameters of a dc discharge in a non-uniform magnetized plasma were measured using fast floating double Langmuir probes. A solenoid is used to produce a uniform magnetic field parallel to the discharge axis. The axial changes of the plasma parameters are presented in the range of longitudinal magnetic fields 200 to 600 Gauss at the pressure range 0.3 to 2.1 Torr and discharge currents 5 and 15 mA in argon gas. The experimental results indicate that, as a consequence of the axial magnetic field and the variations in the discharge tube radii, the plasma parameters at small radius exhibit obvious changes in their distributions along the axis compared to the situation of unmagnetized plasma. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.