Four new anti hypertensive piperidinylmethylphenol compounds were synthesized for their potential antihypertensive and antiarhythmic properties. The pK(a) values were determined experimentally, with the aid of the program SQUAD, by capillary zone electrophoresis (CZE) at T = 298.15 K and 0.015 M ionic strength (I = 0.05 M) and by UV spectrophotometry at pseudophysiological conditions (T = 310.15 K and I = 0.15 M), obtaining good agreement between the values determined with both techniques. A theoretical study was followed in order to propose a deprotonation mechanism for each compound.