A track sensitive deuterium target surrounded by neon-hydrogen mixtures in the 4.4 to 5.0 mole % H2 concentration range was successfully operated in the 85 cm bubble chamber at DESY. The sensitivity limits for bubble formation in these mixtures were determined at 30.5 and 31.5°K. For different expansion pressures the bubble densities in the deuterium and in the mixtures were evaluated. The proportion of hydrogen admixture permissible for simultaneous operation of a deuterium target ranges between about 4.5 and 8 mole %. No phase shift in the pressure-time relation of the target and of the chamber could be observed. The target failed after 18 000 expansions due to Mylar(R) rupture at its cylindrical part where, for future experiments, increased thickness for improved performance can easily be provide. Continuing the experiment with the non-operative target, the limits of sensitivity for bubble formation in the 90/10 mole % Ne/H2 mixture region were established at 28 and 29°K.