Microsoft's .NET Framework, and JAVA platforms, are based in a just-in-time compilation philosophy. Software developed using these technologies is executed in a hardware independent framework, which provides a full object-oriented environment, and in some cases allows the interaction of several components written in different programming languages. This flexibility is achieved by compiling into an intermediate code which is platform independent. Java is compiled into ByteCode, and Microsoft .NET programs are compiled into MSIL (Microsoft Intermediate Code). However, this flexibility comes with a price. With freeware tools available in Internet, it is quite easy to decompile intermediate codes and obtain a working, readable version of the source code. Obfuscation is the most accepted and commercially available technique that developers can use to protect their intellectual property In this work, we propose the use of try-catch mechanisms available in .NET as a way to improve the quality of one of the building blocks of obfuscation: opaque predicates.Facultad de Informática