The father of three children reported missing from St Leonards-on-Sea was arrested last night at Stanford-le-Hope, Essex.
The 48-year-old was detained by Essex Police.
He is now in custody at Hastings police station awaiting interview on suspicion of child neglect.
The three children, aged eight, four and one, were found with him and are now being cared for.
Earlier yesterday, the children's mother, 34, was arrested on suspicion of child neglect after she handed herself in to Hastings police station. She has been bailed until 2 May while enquiries continue.