Recycling of waste glasses has been conducted by a hydrothermal hot-pressing method to produce high density compacts. Our research was focussed on the intluence of various reaction variables (temperature, time, water content and loading pressure) during compaction of several types of waste glasses. The compaction of all glasses starts around 120°C and proceeds rapidly with increasing temperature. Under hydrothermal hot pressing conditions, the compaction of the waste glass is most strongly controlled by temperature and water content, and affected to a lesser degree by reaction time and loading pressure. A maximum tensile strength of 65 MPa was obtained for ‘blue’ glass at 200°C, 10wt% water content, after applying 60 MPa loading pressure for 2 hours.