A sensitivity analysis is performed for the expected changes to the photodissociation rates of various key species that are relative to tropospheric chemistry, due to changes in the radiative transfer, caused by contrails and clouds generated from the use of hydrogen as fuel. The results are compared to those which correspond to contrails from conventional aircraft. For the determination of cirrus clouds as a model input the cirrus clouds climatology developed in the frame of the ISCPP has been used. The optical parameters of the contrails generated by conventional fuel and hydrogen fuel are adopted from the recent literature. The mean total ozone field, which corresponds to present status and has been used as an input is based on both TOMS and ground-based data, while for the future projections the IPCC 1999 scenario has been used. The Tropospheric Ultraviolet and Visible (TUV) radiative transfer model has been used, to calculate the actinic flux in the UV and visible part of the spectrum, at 3-km height steps in the troposphere. For this purpose, the model has been initially tested against spectral measurements, and an agreement of +/- 10% has been achieved when the appropriate input parameters are well documented. The different optical properties of the aerosols and clouds have been considered in the model calculations. For the calculation of the photodissociation rates the latest available chemicokinetical data have been incorporated into the model. It was found that the additional perturbations induced from contrails are larger for the kerosene contrails compared to the ones induced by LH2 contrails, since they are expected to have smaller optical depths.