Fully radioactive waste glasses produced in a hot vitrification pilot plant were characterized in the hot cells at the JRC-Karlsruhe. The work includes microstructural analysis before and after leaching by SOXHLET extractors (MCC-5S), as well as leachate and gel-layer chemical analysis. Partial devitrification, with phases enriched in metals and rare earths, was observed in one of the products. In the gel layers formed during the dissolution tests, enrichment in some elements (Fe,Ti,Gd,Nd,Ce) and depletion in glass constituents (Si,B,K,Ba,Ca,Na) as well as in Mo and Cs, were determined. This was in good qualitative agreement with the leachate chemical analysis.