In this paper, we present an experimental study of the occurrence of different flow modes between two coaxial rotating spheres. The electrodiffusion (ED) method and the visualization technique were used to determine the various flow regimes for an aspect ratio Gamma = H/d ranging from 18 to 21, and for different values of the Taylor number Ta. The dimensionless gap has width beta = 0.107. The inner sphere rotates while the outer one is at rest. The visualization allowed to identify several bifurcation paths during the laminar-turbulent transition. Furthermore, the ED method permitted the measurement of the coefficient of friction in the inner wall of the outer sphere. The flow is analyzed by varying the iso-correlation and the phase space obtained by the ED method.