Program analyses are an important tool to check if a system fulfills its specification. A typical implementation strategy for program analyses is to use an imperative, general-purpose language like Java, and access the program to be analyzed through libraries that offer an API for reading, writing and manipulating intermediate code, such as BCEL or ASM for Java bytecode. We claim that this hampers reuse and interoperability. In this paper we propose a complete ECore-metamodel for Java bytecode, which can be used as a common basis for arbitrary program analyses. We provide tools to generate instances of our bytecode metamodel from Java code in class file format to and vice versa. Code analyses as well as instrumentations can then be defined as model transformations in a declarative, domain-specific language. As a consequence, the implementation of program analysis becomes more concise, more readable and more modular. We demonstrate the effectiveness of this approach by two case studies: profiling of timing performance and model checking of reachability requirements.