Abstract Bi acts as a surfactant in molecular beam epitaxy (MBE) growth on GaAs(100). Incorporation is achieved by disequilibrium at growth temperatures below ∼450°C. Bi can however affect the static reconstruction up to 600°C. Two reconstructions are considered in this work: dynamic (2×1) and static c(8×3)/(4×3), which are shown to be the dominant reconstructions for GaAsBi MBE. Bi storage in these two reconstructions provides an explanation of RHEED transitions that cause unintentional Bi incorporation in the GaAs capping layer. Finally dynamic observations of the (2×1) reconstruction are used to explain growth dynamics, atomic ordering and clustering observed in GaAsBi epilayers which have a direct influence on photoluminescence linewidth broadening in mixed anion III–V alloys.