An Ospreys statement reads: "As the first batch of Ospreys players report back for duty after the summer lay-off, there is good news on the injury front with the six players who have undergone surgery in recent months all on target to return to action on schedule."
Wales scrum half Phillips, 25, underwent anterior cruciate ligament reconstruction to the right knee at the start of April and is targetting a September return.
Ospreys Physio Chris Towers said: "An ACL reconstruction will always require somewhere in the region of a six month rehabilitation programme and Mike is three months into it.
"He is recovering well and at this stage is easily achieving all his targets in terms of physical recovery and is starting to develop his strength and power. Over the next week or so he'll resume controlled skill sessions, but he is still a long way from full contact work. He is on target to return at the end of September or early October."
Henson, 26, also underwent keyhole surgery in April to repair ankle ligaments damaged during last season's Heineken Cup quarter-final defeat to Saracens. And with the recovery process well underway, the British Lions centre could now miss only a few weeks of the new season.
Towers said: "Gavin is still in a walking plaster, which is scheduled to come off on July 10th. Once it has been removed then we'll be looking at working closely with him to get it functioning properly. The indications are that the ankle is coming along well and we are looking towards Gavin returning to action towards the latter end of September."
Meanwhile Wales fullback Lee Byrne, Scotland wing Nikki Walker and veteran prop Andrew Millward have returned to full training following minor operations, though young flanker Ben Lewis is not expected back until November following knee reconstruction.
Towers added: "Ben is just six weeks into his post-op rehab but is responding well and is on course for the standard six-month return to action for an ACL reconstruction, which would see him return to action in November."