Strand displacement reactions underlie dynamic nucleic acid nanotechnology. The kinetic
and thermodynamic features of DNA-based displacement reactions are well understood and
well predicted by current computational models. By contrast, understanding of RNA/DNA
hybrid strand displacement kinetics is limited, restricting the design of increasingly complex
RNA/DNA hybrid reaction networks with more tightly regulated dynamics. Given the
importance of RNA as a diagnostic biomarker, and its critical role in intracellular processes,
this shortfall is particularly limiting for the development of strand displacement-based
therapeutics and diagnostics. Herein, we characterise 22 RNA/DNA hybrid strand
displacement systems, alongside 11 DNA/DNA systems, varying a range of common design
parameters including toehold length and branch migration domain length. We observe the
differences in stability between RNA-DNA hybrids and DNA-DNA duplexes have large effects
on strand displacement rates, with rates for equivalent sequences differing by up to 3 orders
of magnitude. Crucially, however, this effect is strongly sequence-dependent, with RNA
invaders strongly favoured in a system with RNA strands of high purine content, and
disfavoured in a system when the RNA strands have low purine content. These results lay the
groundwork for more general design principles, allowing for creation of de novo reaction
networks with novel complexity while maintaining predictable reaction kinetics.