The results of a computer code modeling the radial diffusion of equatorially confined energetic electrons in Jupiter's inner magnetosphere are compared with spacecraft as well as ground‐based radio (synchrotron radiation) data. We find that the synchrotron radiation spectrum cannot be reproduced without a significant hardening of the electron spectrum betweenL= 3 andL= 1.5. This hardening may be due to energy degradation by Jupiter's ring particles. Our calculations also suggest that there may be larger‐sized material outside Jupiter's ring up to L ∼ 4 or Io's