Samsung has started the process of updating its Galaxy S2 smartphones with the latest version of Android.
Korean S2 owners as well as those in Poland, Hungary and Sweden will start to get the update from 13 March.
The update will gradually be rolled out to other markets and is expected to hit the UK on 19 March.
Changes in Android 4.0, known as Ice Cream Sandwich, include refinements to the touchscreen and letting owners unlock a phone with their face.
The electronics firm announced that the update to Android 4.0 was imminent via its corporate Twitter account.
Samsung was a launch partner for Android 4.0 and its Nexus handsets were among the first to use it. However, owners of the Galaxy S2 have had to wait for their update.
The S2 has been a hugely popular device for Samsung and the firm claims to have sold more than 22 million handsets since its launch in February 2011. It helped Samsung become the world's biggest seller of smartphones in late 2011, according to figures from industry analysts Gartner.
Android-based smartphones are by far the most popular category. Gartner estimates that more than 52% of smartphones are Android based. By comparison Apple has a 15% share of the market.
Stuart Miles, founder and chief executive of gadget site Pocket-lint, said the update was likely to be welcomed by S2 owners.
"It comes five months after the first Ice Cream Sandwich device from Samsung but the update is better than nothing," he said.
How quickly owners can update their device depends on their network operator and whether they have unlocked their phone. Some operators may take a long time to push the software out to customers' devices.
"There are lots of handsets out there that still haven't got the update or won't ever get the update," said Mr Miles.
Samsung said it was planning to update its Note and Tab products with Ice Cream Sandwich soon but has not yet given a date.