For dodec-1-yl thiol SAMs on gold surfaces, the order-disorder transition temperature is 50 °C, while the desorption temperature is 110 °C. The headgroup-substrate affinity will affect these values, so it is not possible to determine whether an order-disorder transition or desorption is the primary cause of the substantial increase in reactivity of the dodec-1-yl ZDDP above 80 °C.