1) Chemical process 
Decaffeination is the removal of caffeine from coffee beans, cocoa, tea leaves and other caffeine-containing materials. (While soft drinks which do not use caffeine as an ingredient are sometimes described as `decaffeinated`, they are better termed `uncaffeinated`. Decaffeinated drinks contain typically 1–2% of the original caffeine content,...
(from the article `coffee`) Caffeine can be removed from the green coffee by a variety of methods. In the most common, solvent extraction, the beans are steamed to raise the ...
Coffee with 97% or more of its naturally occurring caffeine removed is classified as decaffeinated.