Sivia and Rawlings, described as close friends for decades and who co-wrote a book, had fallen out over academic matters while they were at Sivia's house after a meal at a local pub.
Rawlings died after Sivia restrained him in January this year in a headlock when he became aggressive and violent. He suffered a heart attack.
The inquest heard Rawlings was being treated for mental health issues before his death and was restrained after attacking Sivia.
The coroner at Oxford Coroner's Court recorded a verdict of accidental death.
Sivia, 49, was arrested at the time but later released without charge.
Friends of the St Peter's College fellow told the inquest he had been acting strangely few hours before the incident on January 11.
Sivia told the inquest that he feared for his life when Rawlings attacked him "like a man possessed" after becoming delusional and paranoid. He has claimed Rawlings punched him on the face.
He said: "All of a sudden he took up a statuesque pose with a look in his eyes that I had never seen before.
"He sat bolt upright with his fists closed and a menacing look in his eyes. Then he said quietly 'I am going to kill you'."
A video footage of Sivia being questioned by police was shown in which he demonstrated how he had attempted to restrain his friend.
During the interview, he said: "Initially I did have him pinned down to the floor because I just wanted him to calm down".
After demonstrating on his solicitor how he had restrained his friend, Sivia told police: "Most of this time I was just trying to control him like that to stop him attacking me".
The two academicians had been friends for 30 years and had published a book together in 1999, called Foundations of Science Mathematics.
Rawlings, who had a pivotal role in the redevelopment of Goonhilly Satellite Earth Station in Cornwall, was said to be a respected and well-liked academic.
At the time of his death, Rawlings wife rallied in support of Sivia and in a statement issued through police, she said: "I do not believe Steve's death is murder and I do not believe Devinder should be tarnished in this way."
London: Dr Devinder Sivia, an Indian-origin Mathematics lecturer, has been cleared of killing his longtime friend and associate Prof Steven Rawlings, an international acclaimed astrophysicist after the Oxford Coroner's Court declared it as accidental death.
First Published: Saturday, December 01, 2012, 19:09