Resistance-heated ceramic vaporizer boat (10) comprising an elongated vaporizer body having an upper side (1) and a lower side (2) being parallel to each other, and the vaporizer body having plane lateral side surfaces (3) being non-parallel to each other, wherein each of said lateral side surfaces (3) is inclined by an angle of 45.degree. with respect to the upper side (1). Preferably, the end portions at the longitudinal ends of the vaporizer body are reduced, at the lower side (2) thereof, to a predetermined partial thickness (t), whereby a cavity at the upper side (1) of the vaporizer body can be omitted.