The display of emotion at talks with Chinese officials, which included wiping his eye, was rare for Kerry, whose wife Teresa Heinz Kerry, 74, was rushed to a Boston hospital on Sunday from their summer home on Massachusetts' Nantucket island with "seizure-like" symptoms.
The State Department has provided few details about her condition beyond saying that doctors have ruled out a stroke, heart attack or brain tumor as causing her symptoms.
A philanthropist and heiress, Heinz Kerry was improving and remained in fair condition at Massachusetts General Hospital, the State Department said on Tuesday.
"Teresa is doing better, under evaluation and, we hope, improving," Kerry said at the opening session of the annual U.S.-China Strategic and Economic Dialogue. "I want to thank everybody for the remarkable outpouring of good wishes.
"We are very, very humbled by the expressions of support. I think she is coming along. And I know when she is able to she will thank everybody herself," he said in an emotional tone.
Heinz Kerry, who was born in the southern African nation of Mozambique, was married to Republican Pennsylvania Senator John Heinz III, an heir to the Heinz food fortune, until his death in a 1991 helicopter crash.
She married Kerry, who at the time was a Democratic U.S. senator from Massachusetts, on Nantucket in 1995.
Kerry's second wife, Heinz Kerry is the chairman of the Heinz Endowments and the Heinz Family Philanthropies. She is active in environmental issues, has served on numerous boards and has been awarded 10 honorary degrees, according to the Heinz Endowment.
(Reporting by Arshad Mohammed; Editing by Bill Trott)