Sayed Parwez Kambakhsh was convicted in January of insulting Islam.
24-year old Kambakhsh in his cell in Pul-i-Charkhi Prison in Kabul
But at the appeals court in Kabul the 24-year-old insisted he was innocent of all the charges.
He said he was tortured into confessing that he had disrupted university classes by asking questions about women's rights under Islam.
He was also convicted of distributing an article on the same subject, and adding three additional paragraphs.
He told the crowded, hour-long appeal hearing: "As a Muslim ... I never allow myself to do such a thing. These are totally lies."
Kambakhsh's death sentence was handed down during a closed-door trial, which drew condemnation from parts of the international community.
He was studying journalism at Balkh University in the northern Afghan city of Mazar-i-Sharif, and writing for local newspapers, when he was arrested in October.
Our correspondent in Kabul, Martin Patience, says critics accuse the fledgling Afghan justice system of being too religiously conservative.
The journalist's appeal hearing was adjourned for a week, in order to give him time to prepare his written defence.