Complaints against Devon and Cornwall Police rose by 2% to 1,048 during 2011-12, figures released by the Independent Police Complaints Commission show.
The commission has published its annual police complaints statistics for all 44 police forces in England and Wales.
Devon and Cornwall received 1,048 complaints – up from 1,028 in 2010-11 – containing 1,648 allegations.
Only half of those were recorded within ten working days, the lowest rate in the country and a significant fall from the 82% in 2010-11. The force also took 129 days to finalise complaints, the second longest period nationally.
There were also 164 appeals to the Independent Police Complaints Commission from members of the public about Devon and Cornwall's handling of their complaints. Of the 137 appeals completed by the IPCC, it upheld 65, or 47%.
A spokesman for the force said: "Although there has been a slight increase in the number of complaints recorded against officers and staff, compared with the same period last year, we believe that this shows that the public are increasingly confident in making a complaint and knowing that it will be dealt with seriously, which helps to improve the relationship we have with the public in Devon, Cornwall and the Isles of Scilly.
"We have seen an improvement in the way low level complaints, such as verbal disagreements with police officers, are resolved with these types of complaints reducing.
"While this can always be improved, we continue to train and educate staff so that complaints are dealt with and resolved in as quick a time as possible.
"We accept that we still have work to do in some areas such as recording cases within ten working days of the complaint having been made and measures have already been put in place to address this."
The spokesman stressed the "vast majority" of complaints were "not serious" and were "dealt with amicably with the aggrieved person".
He added: "Although the force has seen a 5% increase in the number of allegations made, 81% of those investigated were found to be unsubstantiated with 19% being upheld.
"There will be times when the force is asked to look at how it deals with incidents and we are always open to learning and striving to improve performance in this area.
"The public should quite rightly feel they can contact the police with any grievance they may have and be confident it will be properly and impartially investigated. The IPCC as an independent body can also help and support this process."
Nationally, the total number of complaints recorded by police forces in England and Wales fell by 9% to 30,143. The number of appeals made to the IPCC is increasing as is the number of cases it is upholding.