The crimes are said to have been committed recently and were reported earlier this weekend.
Soon after, the man was arrested and remanded in custody on Tuesday in Gävle district court.
The man, who is temporarily staying in Gävle, must be familiar with the vulnerable person from before, but they must not have any family relationship.
Several different crimes
The suspicions concern rape against children, sexual abuse against children, gross illegal coercion and gross exploitation of children for sexual posing.
According to the newspaper, the man must have both met the person in question, but also had contact via mobile phone where inappropriate material was sent between them.
Prosecution must be provisionally brought no later than the ninth of August.