Those attending must register and pay for the event by either visiting www.rotchamber.co.nz, or calling (07) 346 3657.
The cost is $25 for members and $30 for non-members and includes lunch.
Chamber chief executive Darrin Walsh said about 50 people had so far registered, "but that's not too bad because our members are always notoriously late in registering".
"We are giving each candidate an initial five minutes to speak and will be very firm on those time frames.
"They will then be asked questions we have prepared before the event and each candidate will get to answer those if they like.
"If there's time, we will open up the floor for more questions."
Mr Walsh said The Hits DJ Paul Hickey will MC the event making sure candidates stick to the questions asked and don't speak for too long.