The extremist Monotheism and Jihad group was blamed for attacks on police, soldiers, and a bank near al-Arish, the provincial capital of North Sinai.
During their trials in 2012, six of the men were present in the courtroom, while another eight were fugitives. Four other men in the case were sentenced to life imprisonment.
Insurgent attacks in the Sinai have spiked since the 2013 toppling of Islamist President Mohammed Morsi. Another group, Ansar Beit al-Maqdis or Champions of Jerusalem, has claimed many of them.