Traffic wardens are to go on strike in a row over issues including pay, poor changing facilities and claims of pressure to increase parking tickets.
Members of Unite in Portsmouth will walk out for 24 hours on Wednesday following two hours of industrial action last week.
Unite convenor Richard White said: "Our members have reluctantly decided to move to full strike action. It is regrettable that we have to take this step, but the attitude of council management has left us with no alternative.
"So far, our members have taken action short of strike and strike actions lasting only an hour, on both occasions, Portsmouth City Council has docked members a full day's pay."