In the modified release per oral medicaments, is important to assure the independence of drug deliverance and pH, in order to avoid significative variations in blood levels that can cause therapeutics lacks or toxic effects. One of the most commercialized medicaments in controlled delivery forms is the theophylline, being in the market more than one dozen of registered trademarks, many delivery systems such as tablets, capsules with pellets or microgranules and in different concentrations: 100, 125, 200 and 300 mg. This written work shows the results of a product marketing as capsulated microgranules with 125 and 300 mg of theophylline. We evaluated the delivery of theophylline at 8 pH values, which cover the conditions inside the gastrointestinal tract. We found that theophylline delivery is within the USP 25 requirements for 2 and 4 assays, but the kinetics and the delivery rate are highly dependent on pH. For pH values lower than 6.4 the delivery process follows a first order kinetics model and a dissolution shelf life between 161 min. and 247 min. as the pH is acidified. For pH values from 6.4 to 8.0 theophylline dissolution follows zero order kinetics and the half-life dissolution decreases from 92 min. to 27 min. as the pH becomes more alkaline.