The owner, Britain’s National Grid, is loading a quantity of fuel on to inbound tanker Asia Vision.
Earlier this month the London-listed National Grid said it wanted to establish a reload system for small vessels at Europe's biggest import facility and launched an open season to gauge demand.
The system will allow imported LNG to be loaded back on to different ships for onward delivery to higher-paying markets.
The Asia Vision is sailing for the terminal from Spain.
Several LNG-receiving terminals in Spain, the Netherlands and Belgium have already boosted revenue by offering reloads, which allow traders to profit from price differences between European, South American and Asian markets.
Subject to approvals, the new service at Isle of Grain could be available from late 2016.
The 15 million tonne per annum terminal was the UK’s first commercial LNG importation terminal, the largest by capacity in Europe and eighth largest in the world – with the ability to supply 20% of the UK’s forecast gas demand.
The facility in Kent, southeast UK, began life in 1982 as an LNG peak storage facility, and was used to support the gas supply grid at times of high demand.
In 2002, with North Sea gas fields declining National Grid converted it into an LNG importation terminal.
Subject to approvals, the new service at Isle of Grain could be available from late 2016.