The optical spectroscopy of the europium ion has been used as a probe of the structure of sol-gel glasses. The fluorescence and optical decay times of the Eu3+ ion were monitored during the different stages of the sol-gel process and changes in these optical properties were interpreted in terms of the constantly changing environment of the Eu3+ ion. Eu3+ doped high temperature fusion glasses were also investigated for comparison purposes. The technique of Fluorescence Line Narrowing was used to investigate both the high temperature and sol-gel glasses. While the high temperature glasses narrowed significantly, the sol-gel glasses did not show any evidence of narrowing. This is interpreted as being due to residual OH still within the glass structure and also clumping of the dopant ions. A study of Cr3+ in sol-gel glasses was also made. It is found that most of the Cr3+ is oxidised to the Cr6+ state even when produced in a reducing atmosphere. High temperature borate an silicate glasses were also investigated in the case of Cr3+ for comparison purposes.