TiO2 is a material commonly used in photocatalysis. It is mostly utilized in a powder form, which primarily consists of the metastable anatase polymorph. Contrary to the stable rutile form, anatase has not been under systematic experimental investigation as a single crystal. In this work, adsorption of simple molecules on the anatase (101) surface was studied by means of Scanning Tunneling Microscopy (STM). STM images of hydrogen, water and CO2 have been obtained. Comparison to published DFT calculations allows determining adsorption configurations of these species. The temperature-dependent behavior of these adsorbates was investigated: for H the lowest temperature where diffusion is found is 250 K. Experimental results indicate hydrogen migration into the subsurface above 350 K, preferably to defect sites. Water shows surface diffusion above 210 K and desorbs at 290 K. It was found that coadsorption of water with O2 and annealing results in formation of terminal hydroxyl groups, which are stable above room temperature. CO2 shows no thermally induced diffusion up to 48 K. Interactions of the adsorbates with the STM tip were studied. H becomes mobile when scanned at high sample bias (> +2.5 V), and can be picked up by the tip. It is possible to drop H atoms back onto the surface by using a negative sample bias. CO2 shows similar movement and desorption at high bias; movement also occurs at low bias (< 1 V). For water, tip-induced movement is very rare; high bias converts H2O into OH and bridging oxygen dimers.