The first production night fighter Mosquitos were designated NF Mk II. A total of 466 were built with the first entering service with No. 157 Squadron in January 1942, replacing the Douglas Havoc. These aircraft were similar to the F Mk II, but were fitted with the AI Mk IV metric wavelength radar. The herring-bone transmitting antenna was mounted on the nose and the dipole receiving antennae were carried under the outer wings. A number of NF IIs had their radar equipment removed and additional fuel tanks installed in the bay behind the cannon for use as night intruders. These aircraft, designated NF II (Special) were first used by 23 Squadron in operations over Europe in 1942. 23 Squadron was then deployed to Malta on 20 December 1942, and operated against targets in Italy.
Ninety-seven NF Mk IIs were upgraded with centimetric AI Mk VIII radar and these were designated NF Mk XII. The NF Mk XIII, of which 270 were built, was the production equivalent of the Mk XII conversions. The centimetric radar sets were mounted in a solid "thimble" (Mk XII / XIII) or universal "bull nose" (Mk XVII / XIX) radome, which required the machine guns to be dispensed with.