Most ATP during cellular respiration is made by oxidative phosphorylation at the inner mitochondrial membrane, specifically on the cristae where the electron transport chain and ATP synthase are located.

Key location in the mitochondrion

  • The electron transport chain (ETC) complexes are embedded in the inner mitochondrial membrane, using high‑energy electrons from NADH and FADH₂ to pump protons and set up a gradient.
  • ATP synthase, also in the inner membrane, lets protons flow back into the matrix and uses that energy to convert ADP to ATP; this produces the vast majority of ATP per glucose in aerobic respiration.

Why this spot makes the most ATP

  • The inner membrane is folded into cristae, which greatly increases surface area so more ETC complexes and ATP synthase molecules can operate at once, boosting ATP output.
  • Other stages (like the Krebs cycle in the matrix) make only a small fraction of the total ATP; oxidative phosphorylation at the inner membrane generates most of it.

So, when asked “where in the mitochondria the most ATP is made during cellular respiration,” the best answer is: on the inner mitochondrial membrane (cristae), via the electron transport chain and ATP synthase.

Information gathered from public forums or data available on the internet and portrayed here.