A 35-year-old man has been charged over the alleged attempted murder of a 71-year-old in NSW.

Police will allege that about 10.30am on Tuesday, the 35-year-old attempted to suffocate the older man at a home in Macquarie Hills, near Lake Macquarie.

Police said the men were known to each other.

The 71-year-old was able to leave the house and was treated by paramedics.

Police were later notified of the incident and started an investigation.

The younger man was arrested at a home in Macquarie Hill just after 5am today.

He was taken to Belmont Police Station and charged with attempting to strangle or suffocate someone with the intent to murder (DV).

He was refused bail to appear and is set to appear in Belmont Local Court tomorrow.