Over 600 complaints were made to South Yorkshire Police in one year, new figures show.
The complaints, made up of 1,170 individual allegations, were received in the 2015/16 financial year.
It was a nine per cent reduction on the year before.
Nationally, the number of complaints received by police forces across the country has dropped by eight per cent.
The Independent Police Complaints Commission said in South Yorkshire, 24 per cent of cases were investigated formally and 61 per cent were dealt with at a local level.
The IPCC upheld 24 per cent of appeals made about South Yorkshire's complaint investigations - six out of 25.
IPCC chairman, Dame Anne Owers, said: “We know that the police complaints system is over-complex and over-bureaucratic, and that is part of the reason for the inconsistencies between forces.
“Forces can deal with complaints informally through local resolution, but if complaints are so serious that they could result in disciplinary action, they have to formally investigate them. Some forces choose local resolution in over 70 per cent of cases; others investigate over 70 per ent. It is very unlikely that the profile of cases among forces varies so widely; so this appears to be a postcode lottery.
“When complainants are dissatisfied with a local police investigation, they can appeal. Some of these appeals are dealt with by the force itself; others come to the IPCC. We have previously expressed concerns about forces marking their own homework. Overall, the IPCC is twice as likely to uphold an appeal as local forces."
Detective Superintendent David Barraclough, from South Yorkshire Police's professional standards department, said: “The figures released today by the IPCC show that in 2015/16, the number of recorded complaints against SYP fell, as well as the number of appeals by dissatisfied complainants.
“If anyone is dissatisfied with our process, the IPCC can offer an independent assessment. The numbers of appeals upheld by the IPCC against our force is small when compared to the overall number of complaints received, around one per cent - 602 complaints, six appeals upheld.
“I hope this reassures the public that we have a robust complaints process in place, and we always look at ways we can continually improve the service we provide to the public of South Yorkshire.”