Mrs Robinson said she was extremely concerned about what she called the apparent absence of due process that led to his execution on Tuesday.
She also appealed to Iran not to execute three other Bahais who are reported to have been sentenced to death -- saying that their only offence appeared to be that they belonged to a particular faith.
The treatment of the three-hundred-thousand Baha'is in Iran was one of the issues raised by an European Union delegation which visited Teheran last weekend.
The hanging of Mr Rowhani was the first of a Bahai since 1992.
From the newsroom of the BBC World Service
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