Android 6.0 Marshmallow update
The above HTC handsets will receive Android MarshmallowHTC/Twitter

HTC is one of the first OEMs to reveal rollout plans for Google's newest Android 6.0 mobile operating system codenamed Marshmallow. The announcement comes shortly after Google's 29 September event, where Google unveiled its next generation Nexus phones and Pixel C tablet, the first devices to ship with Android Marshmallow.

HTC USA in a tweet post listed a host of smartphones eligible to receive the new Android software. These include One M9, One M8, One M9+, One E9+, One E9, One ME, One E8, E8 EYE, Butterfly 3, Desire 826, Desire 820 and 816. The company has not provided specific dates for the rollout, but noted that it will start with flagship One M9 and M8 before the end of 2015, with the rest of the devices to follow eventually.

The above devices are in the initial list the company is currently working on. The list will be updated with more devices, HTC further tweeted in response to a query related to the update for other handsets. The Desire 820, which is still sitting on KitKat, will be directly upgraded to Android Marshmallow as version 5.1 is a minor update against the major improvements of Marshmallow, the company confirmed.

As for the 2013 One series flagship One M7, HTC says the device received update throughout its two-year life cycle and now it is out of the life cycle's window for updates. Same is the case with the large-screen One Max. The list of phones issued by HTC matches with what recognised developer LlabTooFeR had predicted ahead of the official announcement.