diff --git a/erc1191/build.gradle.kts b/erc1191/build.gradle.kts
new file mode 100644
index 00000000..2b86efc7
--- /dev/null
+++ b/erc1191/build.gradle.kts
@@ -0,0 +1,7 @@
+dependencies {
+    "implementation"(project(":model"))
+    "implementation"(project(":keccak_shortcut"))
+    "implementation"("com.github.komputing:khex:${Versions.khex}")
+    "implementation"(project(":erc55"))
+}
+
diff --git a/erc1191/src/main/kotlin/org/kethereum/erc1191/ERC1191.kt b/erc1191/src/main/kotlin/org/kethereum/erc1191/ERC1191.kt
new file mode 100644
index 00000000..c7bbcb26
--- /dev/null
+++ b/erc1191/src/main/kotlin/org/kethereum/erc1191/ERC1191.kt
@@ -0,0 +1,31 @@
+package org.kethereum.erc1191
+
+import org.kethereum.erc55.isValid
+import org.kethereum.keccakshortcut.keccak
+import org.kethereum.model.Address
+import org.kethereum.model.ChainId
+import org.komputing.khex.extensions.toNoPrefixHexString
+import java.util.*
+
+/*
+EIP-1191 Checksum as in https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1191.md
+ */
+
+fun Address.withERC1191Checksum(chainId: ChainId) = "${chainId.value}${hex}".toLowerCase(Locale.ROOT).toByteArray().keccak().toNoPrefixHexString().let { hexHash ->
+    Address(cleanHex.mapIndexed { index, hexChar ->
+        when {
+            hexChar in '0'..'9' -> hexChar
+            hexHash[index] in '0'..'7' -> hexChar.toLowerCase()
+            else -> hexChar.toUpperCase()
+        }
+    }.joinToString(""))
+}
+
+private fun Address.hasValidERC1191ChecksumAssumingValidAddress(chainId: ChainId) = withERC1191Checksum(chainId).hex == hex
+
+fun Address.hasValidERC1191Checksum(chainId: ChainId) = isValid() && hasValidERC1191ChecksumAssumingValidAddress(chainId)
+fun Address.hasValidERC1191ChecksumOrNoChecksum(chainId: ChainId) = isValid() &&
+        (hasValidERC1191ChecksumAssumingValidAddress(chainId) ||
+                cleanHex.toLowerCase() == cleanHex ||
+                cleanHex.toUpperCase() == cleanHex)
+
diff --git a/erc1191/src/test/kotlin/org/kethereum/erc1191/TheERC1191.kt b/erc1191/src/test/kotlin/org/kethereum/erc1191/TheERC1191.kt
new file mode 100644
index 00000000..5fe18420
--- /dev/null
+++ b/erc1191/src/test/kotlin/org/kethereum/erc1191/TheERC1191.kt
@@ -0,0 +1,35 @@
+package org.kethereum.erc1191
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.kethereum.model.Address
+import org.kethereum.model.ChainId
+
+class TheERC1191 {
+
+    val rskMainnet = ChainId(30)
+    val rskTestnet = ChainId(31)
+
+    @Test
+    fun returnsTrueForValidERC1191(){
+        assertThat(Address("0x27b1FdB04752BBc536007A920D24ACB045561c26")
+                .hasValidERC1191Checksum(rskMainnet)).isTrue()
+        assertThat(Address("0x27B1FdB04752BbC536007a920D24acB045561C26")
+                .hasValidERC1191Checksum(rskTestnet)).isTrue()
+    }
+
+    @Test
+    fun returnsFalseForInvalidERC1191(){
+        assertThat(Address("0x27b1fdb04752bbc536007a920d24acb045561c26")
+                .hasValidERC1191Checksum(rskTestnet)).isFalse()
+        assertThat(Address("0x27b1fdb04752bbc536007a920d24acb045561c26")
+                .hasValidERC1191Checksum(rskMainnet)).isFalse()
+        assertThat(Address("0x27b1FdB04752BBc536007A920D24ACB045561c26")
+                .hasValidERC1191Checksum(rskTestnet)).isFalse()
+        assertThat(Address("0x27B1FdB04752BbC536007a920D24acB045561C26")
+                .hasValidERC1191Checksum(rskMainnet)).isFalse()
+    }
+
+
+
+}
\ No newline at end of file
diff --git a/settings.gradle.kts b/settings.gradle.kts
index fd3aa212..84e1caed 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -52,3 +52,4 @@ include(":types")
 include(":uri_common")
 include(":userdoc")
 include(":wallet")
+include(":erc1191")