diff --git a/crates/oxide_compiler/src/opcode.rs b/crates/oxide_compiler/src/opcode.rs
new file mode 100644
index 0000000..dfa2956
--- /dev/null
+++ b/crates/oxide_compiler/src/opcode.rs
@@ -0,0 +1,152 @@
+use std::fmt;
+
+/// OpCode for register-based bytecode VM.
+///
+/// Organized in groups of 16 for readability. Implemented opcodes have
+/// emitter support in the compiler; placeholder opcodes are reserved
+/// for future phases (IC, profiling, parallelization).
+#[repr(u8)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum OpCode {
+    // ── Arithmetic (0x00-0x0F) ──
+    ADD = 0x00,
+    SUB = 0x01,
+    MUL = 0x02,
+    DIV = 0x03,
+    MOD = 0x04,
+    NEG = 0x05,
+
+    // ── Comparison (0x10-0x1F) ──
+    EQ = 0x10,
+    NEQ = 0x11,
+    LT = 0x12,
+    GT = 0x13,
+    LTE = 0x14,
+    GTE = 0x15,
+
+    // ── Control Flow (0x20-0x2F) ──
+    JMP = 0x20,
+    JMP_IF_FALSE = 0x21,
+    JMP_IF_TRUE = 0x22,
+
+    // ── Variable (0x30-0x3F) ──
+    LOAD_VAR = 0x30,
+    STORE_VAR = 0x31,
+    LOAD_CONST = 0x32,
+
+    // ── Call (0x40-0x4F) ──
+    CALL = 0x40,
+    RETURN = 0x41,
+
+    // ── Object Property — placeholders (0x50-0x5F) ──
+    IC_GET_PROP = 0x50,
+    IC_SET_PROP = 0x51,
+
+    // ── Profiling — placeholders (0x60-0x6F) ──
+    PROFILE_TYPE = 0x60,
+    PROFILE_SHAPE = 0x61,
+    PROFILE_BRANCH = 0x62,
+    PROFILE_CALL = 0x63,
+
+    // ── Parallel — placeholders (0x70-0x7F) ──
+    FORK = 0x70,
+    JOIN = 0x71,
+
+    // ── Misc (0xF0-0xFF) ──
+    NOP = 0xF0,
+    HALT = 0xF1,
+}
+
+impl OpCode {
+    pub fn is_implemented(&self) -> bool {
+        !matches!(
+            self,
+            OpCode::IC_GET_PROP
+                | OpCode::IC_SET_PROP
+                | OpCode::PROFILE_TYPE
+                | OpCode::PROFILE_SHAPE
+                | OpCode::PROFILE_BRANCH
+                | OpCode::PROFILE_CALL
+                | OpCode::FORK
+                | OpCode::JOIN
+        )
+    }
+}
+
+impl TryFrom<u8> for OpCode {
+    type Error = ();
+
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        match value {
+            0x00 => Ok(OpCode::ADD),
+            0x01 => Ok(OpCode::SUB),
+            0x02 => Ok(OpCode::MUL),
+            0x03 => Ok(OpCode::DIV),
+            0x04 => Ok(OpCode::MOD),
+            0x05 => Ok(OpCode::NEG),
+            0x10 => Ok(OpCode::EQ),
+            0x11 => Ok(OpCode::NEQ),
+            0x12 => Ok(OpCode::LT),
+            0x13 => Ok(OpCode::GT),
+            0x14 => Ok(OpCode::LTE),
+            0x15 => Ok(OpCode::GTE),
+            0x20 => Ok(OpCode::JMP),
+            0x21 => Ok(OpCode::JMP_IF_FALSE),
+            0x22 => Ok(OpCode::JMP_IF_TRUE),
+            0x30 => Ok(OpCode::LOAD_VAR),
+            0x31 => Ok(OpCode::STORE_VAR),
+            0x32 => Ok(OpCode::LOAD_CONST),
+            0x40 => Ok(OpCode::CALL),
+            0x41 => Ok(OpCode::RETURN),
+            0x50 => Ok(OpCode::IC_GET_PROP),
+            0x51 => Ok(OpCode::IC_SET_PROP),
+            0x60 => Ok(OpCode::PROFILE_TYPE),
+            0x61 => Ok(OpCode::PROFILE_SHAPE),
+            0x62 => Ok(OpCode::PROFILE_BRANCH),
+            0x63 => Ok(OpCode::PROFILE_CALL),
+            0x70 => Ok(OpCode::FORK),
+            0x71 => Ok(OpCode::JOIN),
+            0xF0 => Ok(OpCode::NOP),
+            0xF1 => Ok(OpCode::HALT),
+            _ => Err(()),
+        }
+    }
+}
+
+impl fmt::Display for OpCode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let name = match self {
+            OpCode::ADD => "ADD",
+            OpCode::SUB => "SUB",
+            OpCode::MUL => "MUL",
+            OpCode::DIV => "DIV",
+            OpCode::MOD => "MOD",
+            OpCode::NEG => "NEG",
+            OpCode::EQ => "EQ",
+            OpCode::NEQ => "NEQ",
+            OpCode::LT => "LT",
+            OpCode::GT => "GT",
+            OpCode::LTE => "LTE",
+            OpCode::GTE => "GTE",
+            OpCode::JMP => "JMP",
+            OpCode::JMP_IF_FALSE => "JMP_IF_FALSE",
+            OpCode::JMP_IF_TRUE => "JMP_IF_TRUE",
+            OpCode::LOAD_VAR => "LOAD_VAR",
+            OpCode::STORE_VAR => "STORE_VAR",
+            OpCode::LOAD_CONST => "LOAD_CONST",
+            OpCode::CALL => "CALL",
+            OpCode::RETURN => "RETURN",
+            OpCode::IC_GET_PROP => "IC_GET_PROP",
+            OpCode::IC_SET_PROP => "IC_SET_PROP",
+            OpCode::PROFILE_TYPE => "PROFILE_TYPE",
+            OpCode::PROFILE_SHAPE => "PROFILE_SHAPE",
+            OpCode::PROFILE_BRANCH => "PROFILE_BRANCH",
+            OpCode::PROFILE_CALL => "PROFILE_CALL",
+            OpCode::FORK => "FORK",
+            OpCode::JOIN => "JOIN",
+            OpCode::NOP => "NOP",
+            OpCode::HALT => "HALT",
+        };
+        write!(f, "{name}")
+    }
+}