Yes. In Jain Dharma, the Namokar Mantra can be chanted by both men and women, at any time, including during menstrual periods. There is no authoritative Jain scripture that bans or restricts chanting Namokar specifically because of menstruation. If your local temple or guru has a particular etiquette or practice for periods, you can follow that guidance, but it is not a universal prohibition in Jain scriptures.