A man from Wallingford was arrested on suspicion of causing death by careless driving and driving whilst unfit through drugs.
At just before 8.15pm yesterday, there was a collision between a van and a pedal cycle on the dual carriageway section of the A4130 between Lower Assendon and Bix.
Both the van and the bicycle were travelling westbound towards Bix when the collision occurred.
The cyclist, a 45-year-old man from Henley, was pronounced dead at the scene.
The van driver, a 57-year-old man from Wallingford, was arrested on suspicion of causing death by careless or inconsiderate driving and driving whilst unfit through drugs.
He has since been released under investigation.
The victim’s family have been made aware and are being supported by specially trained officers.
Investigating officer PC Julia Stroud of the Serious Collision Investigation Unit, based at Bicester, said: “First and foremost, our thoughts are with the family and friends of the man who has very sadly died.
“I am appealing for any witnesses to this collision, or who saw the van or cyclist before or at the time of the collision to please get in touch.
“I am especially keen to hear from anybody who has dash-cam footage to please check this and contact police if it has captured anything that can assist this investigation.
“You can do so by making a report online or by calling the 24-hour non-emergency number 101, quoting reference number 43210259113.
“For 100% anonymity, you can also call the independent charity Crimestoppers on 0800 555 111.”