The thermophoresis of a circular cylindrical particle bearing a chemical reaction in a gas prescribed with a uniform temperature gradient in the direction perpendicular to its axis is analyzed. The Knudsen number is assumed to be moderately small so that the fluid motion is in the slip-flow regime with effects of temperature jump, thermal creep, frictional slip, and thermal stress slip at the particle-gas interface. The appropriate governing equations of heat conduction/generation and fluid motion are solved analytically and the thermophoretic velocity of the particle is obtained in closed forms. The thermophoretic velocity is a linear function of the thermal stress slip coefficient whose effect increases with an increase in the Knudsen number. When the composition-dependent factor of the chemical reaction within the particle does not depend on position, the thermophoretic velocity is diminished as the reaction is endothermic and augmented as the reaction is exothermic. When this factor is a function of position, the particle velocity can deflect from the direction of the imposed temperature gradient. For specified system characteristics, the effect of the chemical reaction on the thermophoretic velocity of a circular cylindrical particle is significantly greater than that of a spherical particle due to its smaller specific surface area.