Shareholders voted down the stockholder proposal at their annual meeting Wednesday in Wilmington, with 66 percent of ballots against and 34 percent in favor.
The proposal received less support than when first introduced last year, when it won 43 percent of the vote.
Sponsors of the resolution say having the company's CEO also serve as the board chair could hinder the board's ability to properly monitor the chief executive's performance.
Following last year's vote, DuPont's board increased the responsibilities of the lead director to provide more balance with the combined CEO and chair, and align with criteria of Institutional Shareholder Services, a shareholder advisory firm.
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