diff --git a/src/common/validators/index.ts b/src/common/validators/index.ts
index 8d84142a..2d656f0e 100644
--- a/src/common/validators/index.ts
+++ b/src/common/validators/index.ts
@@ -4,3 +4,4 @@ export * from './stellar-memo.pipe';
 export * from './stellar-address.schema';
 export * from './stellar-address.pipe';
 export * from './zod-error';
+export * from './stellar-asset.schema';
diff --git a/src/common/validators/stellar-asset.schema.ts b/src/common/validators/stellar-asset.schema.ts
new file mode 100644
index 00000000..3b5a45a5
--- /dev/null
+++ b/src/common/validators/stellar-asset.schema.ts
@@ -0,0 +1,14 @@
+import { z } from 'zod';
+
+/**
+ * Stellar asset codes are 1–12 ASCII alphanumeric characters. The native asset
+ * is represented by XLM; issued assets use the same code constraints and carry
+ * their issuer separately in the Stellar SDK layer.
+ */
+export const stellarAssetCodeSchema = z
+  .string({ invalid_type_error: 'Asset code must be a string' })
+  .min(1, 'Asset code is required')
+  .regex(/^[a-zA-Z0-9]+$/, 'Asset code must contain only ASCII letters and digits')
+  .max(12, 'Asset code must be at most 12 characters');
+
+export type StellarAssetCode = z.infer<typeof stellarAssetCodeSchema>;
diff --git a/src/modules/transactions/stellar-transaction-validation.spec.ts b/src/modules/transactions/stellar-transaction-validation.spec.ts
new file mode 100644
index 00000000..e84e6c2b
--- /dev/null
+++ b/src/modules/transactions/stellar-transaction-validation.spec.ts
@@ -0,0 +1,84 @@
+import { describe, expect, it } from 'vitest';
+import { ArgumentMetadata, BadRequestException } from '@nestjs/common';
+import { ZodValidationPipe } from '../../common/pipes/zod-validation.pipe';
+import { stellarAssetCodeSchema } from '../../common/validators/stellar-asset.schema';
+import { createTransactionSchema } from './transaction.dto';
+
+const metadata: ArgumentMetadata = { type: 'body', metatype: Object };
+const basePayload = {
+  walletId: '550e8400-e29b-41d4-a716-446655440000',
+  amount: '10.0000000',
+  recipientAddress: 'GDEGSXLGANKHK7QFOV63XCBHBTZ3YRKUJV7ZB7JMSJQB5CNBRLL5QIG5',
+};
+
+describe('Stellar transaction payload validation', () => {
+  it.each(['XLM', 'USDC', 'USD', 'A1', '123456789012'])(
+    'accepts valid Stellar asset code %s',
+    (asset) => {
+      expect(stellarAssetCodeSchema.parse(asset)).toBe(asset);
+    },
+  );
+
+  it.each([
+    ['', 'Asset code is required'],
+    ['ASSET-WITH-DASH', 'Asset code must contain only ASCII letters and digits'],
+    ['ASSET_WITH_UNDERSCORE', 'Asset code must contain only ASCII letters and digits'],
+    ['TOOLONGASSET123', 'Asset code must be at most 12 characters'],
+    ['USD$', 'Asset code must contain only ASCII letters and digits'],
+  ])('rejects invalid asset code %s with a useful validation message', (asset, message) => {
+    const result = stellarAssetCodeSchema.safeParse(asset);
+    expect(result.success).toBe(false);
+    if (!result.success) expect(result.error.issues[0].message).toBe(message);
+  });
+
+  it('rejects malformed G... public keys and invalid checksums', () => {
+    const pipe = new ZodValidationPipe(createTransactionSchema);
+    for (const recipientAddress of [
+      'G-not-a-valid-key',
+      'gdegsxlgankhk7qfov63xcbhbtz3yrkujv7zb7jmsjqb5cnbrll5qig5',
+      'GDEGSXLGANKHK7QFOV63XCBHBTZ3YRKUJV7ZB7JMSJQB5CNBRLL5QIG4',
+      'CDEGSXLGANKHK7QFOV63XCBHBTZ3YRKUJV7ZB7JMSJQB5CNBRLL5QIG5',
+    ]) {
+      expect(() => pipe.transform({ ...basePayload, recipientAddress }, metadata)).toThrow(
+        BadRequestException,
+      );
+    }
+  });
+
+  it('returns HTTP 400 with field-level details for invalid Stellar transfer payloads', () => {
+    const pipe = new ZodValidationPipe(createTransactionSchema);
+    try {
+      pipe.transform({ ...basePayload, asset: 'USD$', amount: '-1' }, metadata);
+      expect.fail('Expected validation to fail');
+    } catch (error) {
+      expect(error).toBeInstanceOf(BadRequestException);
+      const exception = error as BadRequestException;
+      expect(exception.getStatus()).toBe(400);
+      expect(exception.getResponse()).toMatchObject({
+        code: 'VALIDATION_ERROR',
+        details: expect.arrayContaining([
+          expect.objectContaining({ path: 'asset' }),
+          expect.objectContaining({ path: 'amount' }),
+        ]),
+      });
+    }
+  });
+
+  it('rejects non-positive and over-precision amounts', () => {
+    const pipe = new ZodValidationPipe(createTransactionSchema);
+    for (const amount of ['0', '-0.01', '1.12345678', 'NaN', 'Infinity']) {
+      expect(() => pipe.transform({ ...basePayload, amount }, metadata)).toThrow(
+        BadRequestException,
+      );
+    }
+  });
+
+  it('parses a valid transfer and applies the default XLM asset', () => {
+    const pipe = new ZodValidationPipe(createTransactionSchema);
+    expect(pipe.transform(basePayload, metadata)).toMatchObject({
+      asset: 'XLM',
+      amount: '10.0000000',
+      recipientAddress: basePayload.recipientAddress,
+    });
+  });
+});
diff --git a/src/modules/transactions/transaction.dto.ts b/src/modules/transactions/transaction.dto.ts
index 12555d8b..9ccd4b2d 100644
--- a/src/modules/transactions/transaction.dto.ts
+++ b/src/modules/transactions/transaction.dto.ts
@@ -1,7 +1,8 @@
 import { z } from 'zod';
 import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
 import { stellarMemoTypeSchema } from '../../common/validators/stellar-memo.schema';
-import { stellarAddressSchema } from '../../common/validators/stellar-address.schema';
+import { stellarPublicKeySchema } from '../../common/validators/stellar-address.schema';
+import { stellarAssetCodeSchema } from '../../common/validators/stellar-asset.schema';
 import { ValidationException } from '../../common/exceptions/domain.exception';
 
 const idempotencyKeyPattern = /^[A-Za-z0-9._~-]{1,128}$/;
@@ -39,9 +40,9 @@ export const createTransactionSchema = z
     walletId: z.string().uuid(),
     agentId: z.string().uuid().optional(),
     budgetId: z.string().uuid().optional(),
-    asset: z.string().min(1).max(24).default('XLM'),
+    asset: stellarAssetCodeSchema.default('XLM'),
     amount: amountString,
-    recipientAddress: stellarAddressSchema,
+    recipientAddress: stellarPublicKeySchema,
     memo: z.string().max(128).optional(),
     memoType: stellarMemoTypeSchema.optional(),
     memoValue: z.string().optional(),