Combine the oil, lemon juice , lemon zest , orange zest , cumin, coriander, saffron, cinnamon and pepper in a zip-close plastic bag; and add chicken. Squeeze out the air and seal the bag; turn to coat chicken. Refrigerate, turnign the baf occasionally, at least 2 hours or up to 4 hourss.
Spray the grill rack with nostick spray; prepare the grill. If using wooden skewers, soak them in water for 30 minutes.
Alternately thread the chicken and zucchini onto a 4 ( 10 inch) metal or wooden skewers. Sprinkle the kebabs with salt and place on the grill rack. Grill the kebabs, turning every 2 minutes, until the chicken is cooked through, about 15 minutes. Serve with lemon wedges.