The battery, which Samsung reckons will be in phones by 2010, converts the water to Hydrogen gas and Oxygen (who else is remembering their year 9 chemistry) when the mobile is switched on by reacting with metal inside the fuel cell.
According to Oh Yong-soo, vice president of Samsung Electro-Mechanics' research centre, this is how it works:
"When the handset is turned on, metal and water in the phone react to produce hydrogen gas. The gas is then supplied to the fuel cell where it reacts with oxygen in the air to generate power."
Hit the jump for a diagram half in Korean illustrating the process.
However, Samsung thinks that they'll be able to ditch the changeable fuel-cells within a few years.
"Later handsets will be developed that don't need the hydrogen cartridges to be changed, and would only need to be filled with water."