diff --git a/test/pow-test.js b/test/pow-test.js
new file mode 100644
index 00000000..d833c527
--- /dev/null
+++ b/test/pow-test.js
@@ -0,0 +1,88 @@
+/* eslint-env mocha */
+/* eslint prefer-arrow-callback: "off" */
+
+'use strict';
+
+const assert = require('./util/assert');
+const Chain = require('../lib/blockchain/chain');
+const ChainEntry = require('../lib/blockchain/chainentry');
+const Network = require('../lib/protocol/network');
+
+const network = Network.get('main');
+
+function random(max) {
+  return Math.floor(Math.random() * max);
+}
+
+const chain = new Chain({
+  memory: true,
+  network
+});
+
+describe('Difficulty', function() {
+  it('should open chain', async () => {
+    await chain.open();
+  });
+
+  it('should get next work', async () => {
+    const prev = new ChainEntry();
+    prev.time = 1262152739;
+    prev.bits = 0x1d00ffff;
+    prev.height = 32255;
+    const first = new ChainEntry();
+    first.time = 1261130161;
+    assert.strictEqual(chain.retarget(prev, first), 0x1d00d86a);
+  });
+
+  it('should get next work pow limit', async () => {
+    const prev = new ChainEntry();
+    prev.time = 1233061996;
+    prev.bits = 0x1d00ffff;
+    prev.height = 2015;
+    const first = new ChainEntry();
+    first.time = 1231006505;
+    assert.strictEqual(chain.retarget(prev, first), 0x1d00ffff);
+  });
+
+  it('should get next work lower limit actual', async () => {
+    const prev = new ChainEntry();
+    prev.time = 1279297671;
+    prev.bits = 0x1c05a3f4;
+    prev.height = 68543;
+    const first = new ChainEntry();
+    first.time = 1279008237;
+    assert.strictEqual(chain.retarget(prev, first), 0x1c0168fd);
+  });
+
+  it('should get next work upper limit actual', async () => {
+    const prev = new ChainEntry();
+    prev.time = 1269211443;
+    prev.bits = 0x1c387f6f;
+    prev.height = 46367;
+    const first = new ChainEntry();
+    first.time = 1263163443;
+    assert.strictEqual(chain.retarget(prev, first), 0x1d00e1fd);
+  });
+
+  it('should get block proof equivalent time', async () => {
+    const blocks = [];
+    for (let i = 0; i < 10000; i++) {
+      const prev = new ChainEntry();
+      prev.height = i;
+      prev.time = 1269211443 + i * network.pow.targetSpacing;
+      prev.bits = 0x207fffff;
+      if (i > 0)
+        prev.chainwork = prev.getProof().addn(blocks[i-1].chainwork.toNumber());
+      blocks[i] = prev;
+    }
+
+    chain.tip = blocks[blocks.length - 1];
+    for (let j = 0; j < 1000; j++) {
+      const p1 = blocks[random(blocks.length)];
+      const p2 = blocks[random(blocks.length)];
+
+      const tdiff = chain.getProofTime(p1, p2);
+      assert.strictEqual(tdiff, p1.time - p2.time);
+    }
+  });
+});