A common feature in many helicenes mentioned above is the inclusion of a heteroatom into the helical backbone. This is often highlighted by studies as crucial in influencing the physical and optoelectronic properties of a helicene. However, there are relatively few studies dedicated solely towards investigating synthetic strategies for making a wider range of heterohelicenes based on N-, O-, and S-heterocycles. Existing examples include photochemical methodologies as applied to the synthesis of azahelicenes by the Carrona group and a variety of thiahelicenes synthesised by the Wynberg group. Mallory photocyclisations 39 are one of the most common strategies to access heterohelicenes but nonphotochemical methodologies such as the Scholl reaction, oxidative couplings, and [2+2+2] cycloisomerisations have also been reported. Flow or photo-flow methodologies are an often-overlooked synthetic strategy for accessing heterohelicenes. In particular, photo-flow chemistry may offer advantages over batch chemistry including straightforward scalability and a higher tolerance for the high dilution and potential photodegradation encountered in Mallory photocyclisations. Some examples of helicenes and heterohelicenes synthesised in flow have been reported such as the [2+2+2] cycloisomerisations mentioned above, but only a handful of these explore the preparation of heterohelicenes by photocyclisation. In this work, we report the Mallory photocyclisation of a series of heterohelicenes using a photochemical flow reactor. Most substrates were synthesised within a short 100 s residence time by using a powerful 150 W LED 365 nm lamp, enabling throughputs of up to 195 mg of stilbene per hour. A further elaboration of the products to longer helicenes was possible via a Mallory-cross coupling-Mallory sequence that afforded, for example, non-symmetric di(thieno) [6]helicene 4b in 53% yield over three steps from stilbene 1b (Figure ).