Focus Ireland has said more than 1,000 children under the age of eight are homeless, according to a preliminary report by the charity.
The charity has analysed the age profile of 307 families who entered emergency accommodation between March and October this year.
The preliminary report studied a sample of 630 children.
Almost two thirds of these were under the age of eight and almost 40% were aged four and younger.
Focus Ireland said if that was applied to the total number of homeless children in Ireland, it indicates over one thousand - 1,037 - are aged eight and under.
The charity said it had conducted the first analysis of the age profile of homeless children in Ireland.
The final report to be published next month will also examine the travel times between emergency accommodation and schools.
Tánaiste Joan Burton has said that any child living in temporary accommodation is "deeply regrettable".
Speaking on RTÉ’s Today with Sean O’Rourke, Ms Burton said that a commitment to open a thousand beds around the country, given a year ago, has been fulfilled and 14,000 families and individuals have been given accommodation this year.
Meanwhile, Focus Ireland Director of Advocacy Mike Allen said the ages were shocking and highlight that parents with young children are considerably more vulnerable to homelessness than parents of older children.
"The huge number of very young children is deeply shocking," Mr Allen said.
"It is little over year ago that we put the rights of children in our constitution.
"But when you think of these 1,000 very young children living in emergency accommodation at Christmas, it reminds you of how much more we have to do to make that a reality," Mr Allen said.