Rolls-Royce Merlin II or Merlin III engine. Armament consisted of eight .303-in Browning machine guns, four in each wing. Originally had fabric covered wings, two blade wood fixed-pitch airscrew and was without armour or self-sealing tanks. In 1939 the Mk. I was fitted with either the D.H. or Rotol constant-speed airscrew, ejector exhaust stacks, metal covered wings, armour, etc. In the Battle Of Britian the Hurricane Mk. I accounted for more enemy aircraft than any other type of aircraft and altogether in the first year of the war Hurricane squadrons accounted for more than 1,500 confirmed victories over the Luftwaffe, almost half the total of enemy aircraft destroyed by the RAF in that period. In 1940 the Mk. I was fitted with air cleaner and desert equipment for service in the Middle East.

Rolls-Royce Merlin XX engine with two-speed supercharger. Except for slight alterations to the wings to cater for increased armament, a new engine mounting for the longer engine and strengthening of the fuselage and landing-gear to take care of the increased power and weight, no other structural changes were necessary. There were four basic versions :-

1. Mk. IIA (1940), with Mk. I metal wings equipped with eight machine-guns.
2. Mk. IIB (1940), with two additional guns in each wing outboard of the landing light, to make a total armament of 12 .303-in guns, six in each wing.
3. Mk. IIC (1941), with an armament of four 20mm (.737in), British Hispano cannon, the four cannon wings were initially rebuilt from damaged Mk. I metal wings.
4. Mk. IID (1943), which had an armament of two 40mm (1.575 in), Vickers or Rolls-Royce cannon and two .303in guns, together with additional armour for low attack.

In 1941 both the Mk. IIB and IIC were provided with racks for carrying two 250-lb or 500-lb bombs or alternatively two 45 or 90 gallon droppable fuel tanks, and both were equipped with tropical equipment for service overseas. The Mk. IIB fighter-bomber first went into action over occupied France in November, 1941. In both the fighter-bomber and long-range versions, the Mk. II retained all its qualities as a fighter.

The Mk. III was the British-built Mk. II fitted with the Packard Merlin engine. It was never in production as the Mk. III

Rolls-Royce Merlin 21 or 22 engine. Fitted with wings capable of carrying the following alternative armaments and loads :-

1. Two 40mm Vickers cannon and two .303in guns
2. Eight rocket projectiles and two .303in guns
3. Two 250lb or 500lb bombs and two .303in guns
4. Two 45 or 90 gallon drop tanks and two .303in guns

Also fitted with 350lbs of additional armour. Max speed 314 mph, range 495 miles.

Rolls-Royce Merlin 27 or 32 engine with increased take-off output. Same alternative armament and loads as the Mk. IV. Only two built. (NL255 the prototype, and two converted Mk. IVs to Mk. V standard, (KX405 and KZ193))

Packard Merlin 28 engine driving a Hamilton Standard Hydromatic airscrew. Built in Canada by the Canadian Car and Foundry (CCF) Company Ltd. Corresponded to the British-built Mk. I

Packard Merlin 29 engine. Built by CCF. Corresponded to British-built Mk. II, Mk. IIA, and Mk. IIB.

Rolls-Royce Merlin II or III engine. Conversion from Hurricane Mk. I. In three versions :-

1. Mk. IA, (1941), fitted with catapault spools, slinging gear, and naval radio for use from C.A.M. ships, which were introduced in the spring of 1941 for the air protection of convoys at sea.
2. Mk. IB, (1941), fitted with both catapault spools and deck arrrester gear for aircraft carrier use.
3. Mk. IC, (1942), with the same airframe as the Mk. IB but with Hurricane Mk. IIC four cannon wings.

The first enemy aircraft to be destroyed by a catapulted Sea Hurricane IA was shot down on August 3, 1941. The Mk. IB was the first single-seat carrier fighter monoplane to be used by the Royal Navy. It first went into operation in the Mediterranean in June, 1942, particularly distinguishing itself in the defence of Malta convoys in the summer of that year.

Rolls-Royce Merlin XX engine. Conversion of the Hurricane Mk. II. Fitted with deck arrester gear and naval radio, but without catapault points.

Packard Merlin 29 engine. Canadian built. A conversion of the Hurricane Mk. XIIA.

Some Hurricane IIs were fitted with arrester hooks in 1943 for use as trainers on dummy carrier decks ashore. Unlike the Sea Hurricane Mk. II they retained standard R.A.F. equipment.