A fundamental understanding of surface-reaction kinetics and mechanisms is essential to making progress on rational design of complex surface architectures used in applications as varied as biosensor devices and organic electronic devices. We present recent progress on the understanding of the carbodiimide coupling reaction frequently used to form a surface-tethered active N-hydroxysulfosuccinimide ester and the subsequent substitution of the active ester with various nucleophiles in solution. These studies were carried out using surface-enhanced Raman spectroscopy (SERS) and show that the carbodiimide coupling reaction is first order in carbodiimide concentration and zero order in N-hydroxysulfosuccinimide concentration. This reaction proceeds with a second-order rate constant of 0.062 mM(-1)s(-1) at about 20 degreesC. The tethered active ester was then reacted with histidine or glucose oxidase. The reaction with histidine was found to be first order in the histidine solution concentration, indicating a Simple S(N)2 reaction mechanism with a second-order rate constant of 0.010 mM(-1)s(-1). The reaction with glucose oxidase had more complicated kinetics that were consistent with the formation of a surface bound acylium ion intermediate.