The average values of the electron temperatureTeand the electron densityNein the corona plasmas of spherically irradiated high‐Ztargets have been estimated. Targets composed of the elements Cu through Br, Rb, and Mo were irradiated using the fundamental (1.06 &mgr;m) and the frequency‐tripled (351 nm) output of the Omega laser system. Spectra were recorded in the wavelength region 15–200 A˚. Using various extreme ultraviolet spectroscopic techniques, it is found that for the case of a Mo plasma produced by frequency‐tripled laser irradiation,Te=2600±600 eV andNe>6×1020cm−3. This is consistent with a ‘‘flux limit’’ smaller than 0.1. The estimated values ofTeandNeare lower in the corona plasmas produced using the fundamental (1.06 &mgr;m) irradiation.