Ratings for the first episode of the new series of Lost fell by more than one million, after the cult US drama series moved from Channel 4 to Sky One.
Lost follows plane crash survivors who are stranded on a desert island
The double bill, beginning at 10pm, drew 1.4m viewers, but audience figures fell to 1.2m after the first hour.
When Lost premiered on Channel 4 in 2005, it attracted six million viewers. The second series double bill debuted in May with 3.9m, dropping to 2.8m.
A spokesperson for Sky said they were "delighted" with the audience figures.
The figures exceeded the launch of other hit US dramas on Sky One including 24, Nip/Tuck and Bones.
In October, trade paper Broadcast reported that the channel had paid £20m for the rights to the show.
But the Emmy award-winning drama failed to outstrip viewing records for the channel, with an episode of Friends in 2000 still leading the way with an audience of 2.8m.
An episode of The Simpsons, written by Ricky Gervais, secured one of the highest ratings for Sky in 2006, with viewing figures of 2.3 million.
Sunday night's first episode of Lost, which follows the aftermath of an air crash on a desert island, made Sky the third most watched channel across all television networks, including terrestrial.
The second episode put Sky behind Channel 4, who topped the ratings with The Return of the King - the final instalment of the Lord of the Rings film trilogy.