DSM and Martek "have entered into a definitive agreement under which DSM will acquire all the outstanding shares of common stock of Martek for $31.50 in cash per share", a joint statement said.
"The transaction has been approved by DSM's supervisory board and is recommended by Martek's board of directors."
The tender process was expected to close in February next year, and the transaction in the first or second quarter of 2011, the statement said.
DSM manufactures chemicals used in nutrition, health care products, paint, electronics and housing. It has annual net sales of about eight billion dollars and employs about 22,700 people worldwide.
The US-based Martek has about 525 employees and produces nutritional supplements.
Its acquisition would position DSM as a leader in polyunsaturated fatty acids and infant nutrition, the statement said.
"The transaction is not subject to a financing condition, and DSM intends to finance the acquisition from existing cash," it said in a statement.