  Using the complex Klein-Gordon field as a model, we quantize the quaternionic
scalar field in the real Hilbert space. The lagrangian formulation has
accordingly been obtained, as well as the hamiltonian formulation, and the
energy and charge operators. Conversely to the complex case, the quaternionic
quantization admits two quantization schemes, concerning either two or four
components. Therefore, the quaternionic field permits a richer structure of
states, if compared to the complex scalar field case. Moreover, the
quaternionic theory admits as a further novel feature a non-associative
algebraic structure in their complex components, something not observed in the
complex case.
