Fifteen schools in the city are to offer the meals to all pupils from next month and all primaries in the authority are due to follow by next year.
Councillors hope the free lunches and breakfasts will improve the children's concentration and behaviour and help lift the city's poor test results. Hull is bottom of the GCSE league tables in terms of pupils attaining at least five A-C grades.
The scheme is also expected to remove the stigma that drives pupils from lower-income families to refuse free meals. Currently, 26 per cent of Hull primary pupils are entitled to free meals.
At Francis Askew primary the number of children eating school meals dropped last year when it began offering healthier lunches.
Headteacher Linda Calvert said pupils had initially been deterred by the lack of chips but added that baked potatoes were steadily growing in popularity.
Although the school hopes all pupils will opt for the free meals, teachers believe some parents may still prefer to make their children's lunches.
"One or two parents have said it will save them money," Mrs Calvert said.
"But I am sure some will carry on sending packed lunches, which is a shame because they can be full of additives."
Late last year the Welsh Assembly voted to give all primary children a free and nutritious breakfast by September 2006. Only 34 of Wales 1,700 primaries currently offer breakfast.
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