People will be able to register their interest in buying Mighty River Power shares tomorrow.
Cabinet has passed an order of council that allows the SOE to be partially put up for sale.
Mighty River Power will have secondary listing on the Australian Stock Exchange.
Prime Minister John Key says people will have about three weeks to register, but it won't bind them into buying any shares.
Finance Minister Bill English and State Owned Enterprises Minister Tony Ryall will officially launch the interest process at Mighty River Power headquarters tomorrow.
Tony Ryall they've narrowed the definition of what a New Zealander is when it comes to eligibility for getting shares.
He says they'll have to be a new Zealand citizen or resident, have an IRD number, a domestic bank account and a New Zealand address
$1.1 million dollars has been set aside to pay for a mass media campaign promoting the pre-registration process for Mighty River Power shares.
Tony Ryall says the campaign begins tomorrow and will be across television, newspapers and the internet.
He says if the level of pre-registration is very strong that may be dialled back, but at this stage, $1.1 million dollars has been set aside.
Opposition parties believe Kiwis won't be at the front of the queue for long.
New Zealand First leader Winston Peters says loopholes will be exploited and shares will soon find their way into the hands of foreigners.
Greens co-leader Russel Norman says a secondary listing on the Australian Stock Exchange will also see shares go offshore, no matter what the Government promises.
Photo: Whakamaru Hydro Dam - Mighty River Power (supplied)