Advanced studies of atomic and molecular systems require very precise probes with a few Angström space resolution and a few attosecond time resolution. High Harmonic Generation (HHG) satisfies these two requirements in a single tool: during this process, an intermediate step is the formation of an electronic wave packet in the continuum, whose central wavelength and duration perfectly match the spatial and temporal resolution required. HHG also provides a powerful source of ultrashort coherent XUV radiation for photoionization studies. The aim of this project is to investigate electronic wave packet (EWP) dynamics in molecules by combining different methods using the HHG process. It will be split in 3 tasks: (1) Investigation, using the self-probing scheme, of the EWP dynamics resulting from tunnel ionization in small Hydrocarbons, for instance ethylene (C2H4) or ethane (C2H6); this will be done in particular through a full mapping of the harmonic phase obtained by combining RABITT and harmonic interferometry experiments. This will allow precise determination of the shape and location of the hole created during tunnel ionization. (2) Measurement of the amplitude and phase of the photoionization dipole matrix elements of the same molecules by ionization with an attosecond pulse train within a weak IR field; moreover, the influence of resonant states on the ionization process will be investigated by scanning the XUV-wavelength across a resonance. This should give access to the attosecond time delay of the photoelectron emission in the two-color ionization process. (3) Implementation of a multicolour setup by mixing 400 nm, 800 nm and 1600 nm pulses to achieve a better control of the continuum electron wave packet in the HHG process. This will extend considerably the range of applicability of the self-probing scheme. All this will lead finally to a better understanding of the underlying processes and give multiple insights into the attosecond dynamics in molecules.