This work assessed the effectiveness of several methods on degradation of microcystin-LR (MC-LR) by different Advanced Oxidation Processes, like solar photo-Fenton, UV-A/photo-Fenton and UV-C/H2O2. UV-C/H2O2 and UV-A/photo-Fenton processes were carried out in a bench scale photochemical apparatus and the solar photo-Fenton treatment was performed in a CPC photoreactor. MC-LR degradation was monitored by LC-ESI-MS/MS and kinetic parameters were calculated for all systems evaluated. The results demonstrated that UV-C/H2O2 was the most efficient method, showing a reduction of over 90% of initial MC-LR after 5 min of reaction. Solar and photo-Fenton/UVA had a rate decrease of 88 and 76% after the same time, respectively. The kinetic study indicated that the solar photo-Fenton and artificial radiation (UV-A) processes were very similar in their efficiency. The use of sunlight instead of artificial UV radiation significantly reduced the cost of photocatalytic treatment systems; it is also an environmentally friendly method, since it utilizes renewable energy.