diff --git a/.changeset/hex-tonumber-empty.md b/.changeset/hex-tonumber-empty.md
new file mode 100644
index 00000000..fccf0c0f
--- /dev/null
+++ b/.changeset/hex-tonumber-empty.md
@@ -0,0 +1,5 @@
+---
+"ox": patch
+---
+
+Fixed `Hex.toNumber` (and `Bytes.toNumber`, which delegates to it) returning `NaN` for empty hex (`0x`) instead of throwing, consistent with `Hex.toBigInt`.
diff --git a/src/core/Hex.ts b/src/core/Hex.ts
index fcf6e853..fd8a59c6 100644
--- a/src/core/Hex.ts
+++ b/src/core/Hex.ts
@@ -665,7 +665,12 @@ export declare namespace toBytes {
  */
 export function toNumber(hex: Hex, options: toNumber.Options = {}): number {
   const { signed, size } = options
-  if (!signed && !size) return Number(hex)
+  if (!signed && !size) {
+    const number = Number(hex)
+    // `Number('0x')` is `NaN`; defer to `toBigInt` so empty hex throws
+    // instead of silently returning `NaN` (consistent with `Hex.toBigInt`).
+    if (!Number.isNaN(number)) return number
+  }
   return Number(toBigInt(hex, options))
 }
 
diff --git a/src/core/_test/Hex.test.ts b/src/core/_test/Hex.test.ts
index 950b5a7c..d3a5e187 100644
--- a/src/core/_test/Hex.test.ts
+++ b/src/core/_test/Hex.test.ts
@@ -641,6 +641,11 @@ describe('toNumber', () => {
       '[Hex.SizeOverflowError: Size cannot exceed `32` bytes. Given size: `64` bytes.]',
     )
   })
+
+  test('error: empty hex', () => {
+    // Consistent with `Hex.toBigInt('0x')`, which throws. Must not return `NaN`.
+    expect(() => Hex.toNumber('0x')).toThrow()
+  })
 })
 
 describe('toString', () => {