Pc Terry Price, who serves as a Sussex Police officer based at Horsham, was accused of attacking a woman in October last year.
Price, 54, of Southwater, near Horsham, West Sussex, was cleared of rape following a trial at Maidstone Crown Court, police said.
Following the case, Superintendent Mark Eyre, of Sussex Police, said: "We, of course, respect the jury's verdict.
"People should be reassured that serious allegations - whether against members of the public or police officers - will be taken seriously and investigated thoroughly, with information passed to the CPS for consideration of prosecution."
Price remains suspended from the force, a police spokesman said following the acquittal.