Acetylcholinesterase (AChE) is an enzyme playing important role in termination of neurotransmission within cholinergic system. The enzyme is targeted by many compounds including nerve agents used for chemical warfare, natural toxins and drugs for Alzheimer disease. Thousands of new inhibitors are prepared for pharmaceutical purposes over the year and necessity to characterize them is given for this reason. In this work, standard spectrophotometric test is compared to electrochemical test in order to assay AChE activity and measure its inhibition. The both test were performed for characterization of an Alzheimer disease drug galantamine. The spectrophotometric test was based on standard Ellman´s reaction. Electrochemical test used enzymatic hydrolysis to acetylthiocholine with consequent electrochemical oxidation. In the experiments, we proved that electrochemical test was able to reach better limit of detection for galantamine than the standard spectrophotometric test. Calculated median inhibitory concentration was same for electrochemical and spectrophotometric tests. Interference in the assay was tested as well. We proved that electrochemical test is reliable and more sensitive than the standard spectrophotometric test. The electrochemical test would be preferred when median inhibitory concentration is the assayed output.