Results of an underwater electrical explosion of single wires made from Cu and Al are presented and analyzed. Experimental research was carried out using microsecond timescale generators having 33/180 kA, 33/45kV and 1200 ns of current amplitude, resistive voltage, and rise-time respectively. The discharge current was measured by a current viewing resistor or Rogowski coil and the resistive voltage was calculated from the measured voltage by a voltage divider accounting for inductive voltage. These data coupled with data from Optronis Optoscope SC-10 streak camera and 1D MHD simulation was used to study the phase transitions in different metals at extreme conditions, i.e. the moment when a transition occurs, the life-time of a phase and energy density in the wire at the moment of transition.