As the temperature of a fixed volume gas increases, pressure will also increase. This is because as the temperature of a gas increases, the molecules move faster and collide with the walls of the container more frequently and with more force, exerting greater pressure on the container. The relationship between temperature and pressure in a fixed volume gas is directly proportional, meaning that as temperature increases, pressure increases, and vice versa. This relationship is known as Boyle's Law or the Boyle-Mariotte Law.