The chief constable of Thames Valley Police, Jason Hogg, has been suspended from duty amid an investigation into allegations of gross misconduct.
Police and crime commissioner for Thames Valley, Matthew Barber, said the suspension would take effect immediately.
The police watchdog, the Independent Office of Police Conduct (IOPC), is investigating the allegations.
It is claimed Mr Hogg failed to adequately investigate allegations relating to the improper retention of sensitive police information, Mr Barber said.
He said the matters relate to “alleged breaches of the standards of professional behaviour amounting to failure in duties and responsibilities” and a “lack of honesty and integrity”.
There is no criminal investigation into Mr Hogg.
Thames Valley Police, England’s largest non-metropolitan police force, covers Buckinghamshire, Berkshire and Oxfordshire.