A custard-like liquid that hardens when struck is being used to give soldiers greater protection and ease of movement in combat situations.
The technology, dubbed 'liquid armour' by scientists and engineers at defence security company BAE systems, has been designed to fit between sheets of strong material such as Kevlar.
Unlike ceramic-based armour plates used in current body armour systems to cover large areas of the torso, the technology is not heavy and bulky.
Bullet-proof jackets made from the goo could be used within two years.
BAE spokesman Stewart Penney said: "The technology is best explained by the example of stirring water with a spoon.
"In water you feel little resistance to the spoon. Whereas with liquid armour you would feel significant resistance as the elements in the fluid lock together.
"The faster you stir, the harder it gets, so when a projectile impacts the material at speed, it hardens very quickly and absorbs the impact energy."
Trials at BAE Systems' advanced technology centre in Filton have shown the liquid armour allows thinner than standard armour to withstand equivalent levels of forces.
"In addition to increasing the ballistic performance of combat body armour there is potential for developing a version that could be of interest to police forces and ambulance crews," Mr Penney added.