The Oklahoma-based group extracts iodine from brine produced by onshore oil wells.
Two of its plants (IO#3 and IO#5) were offline at the start of the quarter, while parts of the US were hit by one of the coldest winters in living memory.
Even so, the group produced 118.2metric tonnes (118.7Mt) in the three months to March.
A new plant IO#7, the former IO#3 plant repurposed, opened midway, while a review of the best way to optimise production from IO#5 has now started.
Tom Becker, the chief executive, added it was a solid start to 2018 while the ramp-up of IO#7 would increase output and reduce production costs.
"The trend of iodine prices continues to move upward and is an additional benefit,” he added.
As well as iodine extraction plants, Iofina also has an iodine chemical business, which performed as expected in the first quarter.