He said the offenders were disturbed by staff and left quickly taking a large unknown quantity of the acid with them while drums were left behind.
It was possible the offenders were left with chemical burns or dissolved shoes from the spilt acid, Mr Valentine said.
"When they were disturbed they spilled a lot and the tank was siphoned so it continued to leak."
The exact amount the offenders managed to get away with was unknown but 50 to 60 litres was missing from the tank, he said.
"Fifty to 60 litres is of significant value ... It's hard to give a street value as it is only one of a large number of ingredients and goes through a long cooking process."
Police were conducting a scene examination of the chemical yard and investigating the CCTV footage.
The burglars appeared to be well organised with equipment to break through the security fences and siphon and collect the acid, Mr Valentine said.
The staff had taken all the necessary security measures and precautions, he said. A spokesperson for the company was unable to be contacted before the Bay of Plenty Times went to print.
Anyone with information should contact Tauranga police on (07) 577 4300.
Hypophosphorous acid
*It is used in the formulation of pharmaceuticals, discoloration of polymers, water treatment, retrieval of precious or non-ferrous metals.
*Its main use is for electroless plating.