The Mark II Armor was Tony Stark's second Iron Man suit, heavily refining the bulky and rudimentary design of the previous Mark Isuit, resulting in a far more articulated and sleek design. It was described by James Rhodes as "an unarmed prototype of the Iron Man armor".
After returning from captivity in Afghanistan, Tony Stark began designing the Mark II armor, drastically revamping the design of the Mark I using the resources and technology available to him through his company: Stark Industries. Tony started building this suit in stages, experimenting with new technology, mainly to improve the suit's flight capabilities.
Working from his basement workshop Tony started by creating a pair of thruster boots, quickly followed by a pair of palm based repulsor gauntlets to stabilize his flight. Once Tony had perfected the flight thrusters and repulsors he went on to create the armor of the suit itself, making it more sleek and aerodynamic than the Mark I, with articulated control flaps for added flight control and stability.
He also created a user interface using his J.A.R.V.I.S. AI system. During his first control test, Tony decided to take the Mark II on its first full test flight despite J.A.R.V.I.S.'s recommendations. His flight proved to be an outstanding success until testing the suit's altitude limit, during which it demonstrated a near fatal icing problem in the higher altitude.
After this test flight, Tony retired the Mark II suit, preferring to use the finalised, weapons integrated Mark III suit.
The Mark II armor was a complete revamp of the base principle and technology of the rudimentary Mark I armor, using improved resources and new technology that Stark developed specifically for the suit. The original bulky design was considerably streamlined, giving the Mark II a sleek, more human-like appearance. In addition to the more articulated design, this suit also integrated a new user interface system based on Stark's J.A.R.V.I.S. A.I.
The greatest advancement for the Mark II armor was its vastly improved flight capabilities, now capable of sustained flight for long periods of time. This was made possible through Tony Stark's development of sustained flight thruster boots and hand based repulsor gauntlets for flight stability, all derived from and powered by his newly miniaturized arc reactor.
It was discovered that the greatest weaknesses of the Mark II was its high altitude icing problem. Because the suit was still in the experimental stages, it was made of materials not tested for higher altitudes. Thus, when it was exposed to the thin, cold air of the upper atmosphere, a sizable layer of ice would form over its surface, immobilizing the suit and causing a complete system shut-down, proving nearly fatal for the user.
Due to this, the Mark II was retired to make room for the Mark III, which was made out of materials specifically made for interstellar exploration.